Talk:Enzyme kinetics

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Featured article Enzyme kinetics is a featured article; it (or a previous version of it) has been identified as one of the best articles produced by the Wikipedia community. Even so, if you can update or improve it, please do so.
Main Page trophy This article appeared on Wikipedia's Main Page as Today's featured article on October 22, 2007.
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August 29, 2006 Peer review Reviewed
September 24, 2006 Good article nominee Listed
September 29, 2006 Peer review Reviewed
October 3, 2006 Featured article candidate Promoted
Current status: Featured article
edit·history·watch·refresh Stock post message.svg To-do list for Enzyme kinetics:

Here are some tasks awaiting attention:
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    • Work on related articles such as enzyme catalysis
    • Italics in refs needs correcting (minor)
Priority 3

As per discussion on the Enzyme page, I believe this article should be combined with the Rate of enzyme mediated reactions page and the inhibitor section of the Enzyme page. The actual text of this article should probably be replaced with the "new" article.

Hichris 15:44, 6 December 2005 (UTC)

I agree and will watch this page for further action and elp out if possible. David D. (Talk) 19:26, 9 December 2005 (UTC)
Yes, it is obvious that these pages give informations about the same subject : enzyme kinetics. Maybe we should first add what is on the other pages on this page, and then if it's okay, delete the content from the original pages. --Totophe64 13:13, 19 December 2005 (UTC)
Agree. Most of this material is common to the Enzyme article. -CoeurDeLion

suggested merge with Enzyme[edit]

Disagree. Enzyme kinetics is on a deeper scientific level that the enzyme article, and the background given in this article is geared towards that purpose; a merge would make the enzyme article clunky. The internal link from enzymes to enzyme_kinetics is enough to show that this topic is covered. Vermiculus 16:16, 3 April 2006 (UTC)
Disagree. Enzyme kinetics is much more the theory and physics of enzymes. The article under Enzyme is much more the tangible material. Also the vastness and the usefullness of enzyme kinetics makes it essential to be separate, as a matter of fact it should be expanded. A merger with Michaelis-Menten kinetics would be more logical
Disagree. The enzymes page needs to be accessible to the non-specialist and this material would fit poorly. I am in the process of expanding the enzyme inhibitor page and moving some of the stuff from enzymes over to there. The section in this page on inhibition will be replicated and covered in more depth in this new version of enzyme inhibitors. I agree that merging this page with Michaelis-Menten kinetics and Rate of enzyme mediated reactions would be preferable.--TimVickers 23:40, 28 June 2006 (UTC)--TimVickers 23:40, 28 June 2006 (UTC)
Just a little background here. I think the original suggestion was to move things from enzyme to here, not vice versa. There used to be a horrendous enzyme kinetics section in the enzyme article. It contributed to the article being way too long and far too complex for the average reader. Obviously that has since disappeared from the current enzyme article. David D. (Talk) 21:41, 29 June 2006 (UTC)

In fact, there is nothing in the Rate of enzyme mediated reactions page that is not in the other enzyme pages. What about?

  • Enzymes - General introduction
  • Enzyme kinetics - Page divided into kinetics and mechanism. First section covering simple MM kinetics, then multi-substrate reactions and allosteric effects. Second section covering mechanisms of catalysis.
  • Enzyme inhibition - Modes and examples. Mostly finished now.--TimVickers 21:43, 29 June 2006 (UTC)

Looks good to me. This is long overdue. David D. (Talk) 21:45, 29 June 2006 (UTC)

OK, over the next few weeks I will move stuff from MM kinetics to here and then when people are happy with this article the old MM page can be deleted. I suggest we put up the Rate of enzyme mediated reactions page up for deletion.--TimVickers 21:50, 29 June 2006 (UTC)

I'd suggest letting 'Rate of enzyme mediated reactions' lie dormant until the project is complete. Redirecting that page is always an option too. David D. (Talk) 21:59, 29 June 2006 (UTC)

OK, good plan. I'll redirect the links to that page to here.--TimVickers 22:20, 29 June 2006 (UTC)

Stuff moved until I can fit it in to main article--TimVickers 17:19, 1 July 2006 (UTC)

Unanswered Questions[edit]

This article, like the enzyme article and the DNA article, dodges all the fundamental questions in a fairly spectacular manner. I realize that Wiki articles are meant to be about what we know rather than what we don't, but I strongly believe that all science articles that beg fundamental questions so glaringly should post those questions as work for the future. How can nonliving bodies like enzymes, that have no DNA, no hardwiring, no brains, and no switches, perform all these complex tasks? They are used to explain almost everything, especially in the groundwork of DNA replication, and yet their motions are completely mysterious. How do they happen to be in the right place at the right time in the right form? How is it that extremely useful self propelled "blueprints" seem to be universally available? How are they manufactured, how are they read, how is their necessity known before they get there? I am not some crank from the far right, proposing inserting god here. I just think these obvious questions should not be swept under the rug. It looks bad, as science. 00:50, 6 August 2006 (UTC)

How do they happen to be in the right place at the right time in the right form? How are they manufactured, how are they read, how is their necessity known before they get there?

See articles on the control of gene expression, transcription, protein synthesis and sub-cellular localisation of proteins.

How is it that extremely useful self propelled "blueprints" seem to be universally available?

All life involves enzymes, this question relates to the origin of life.

These are a mix of biochemical questions that are dealt with in other articles and interesting philosophical questions. Enzymes are just one class of proteins, so the mechanism and control of their synthesis and activity is not fundamentally different from that of structural proteins, channels or sensory proteins. Therefore these questions are best dealt with in general articles rather than repeated in each page on particular classes of protein.--TimVickers 10:17, 8 August 2006 (UTC)

Good article nomination[edit]

Is it a B-class article? My suggestions:

  • links in the end of section Ternary complex mechanisms; Ping-pong mechanisms should be references.
I deliberately didn't make these references since I want people to look at these at the same time as reading the text and looking at the figure. I thought if I put them as references then most of the readers would miss them.
Ok then at least, it should be written in prose. NCurse work 18:07, 23 September 2006 (UTC)
OK, done. TimVickers 21:58, 23 September 2006 (UTC)
  • in section Enzyme inhibition: images are merged for me (Firefox, 1024*768)
I added more text and moved the image up, which should fix this.
Hmm. Well it says the same amount as the one in the article at the moment, but takes far more space. I tried linking the table and figure more explicitly as an alternative.
  • more external links.
Added some more.

Anyway well-referenced, well-written, you should consider FAC. NCurse work 10:57, 23 September 2006 (UTC)

Thank you, I will - but this is still pretty arcane, needs a lot of work first! TimVickers 17:00, 23 September 2006 (UTC)

It's a good article now. Well done! :) NCurse work 18:14, 24 September 2006 (UTC)

biological significance[edit]

Not really sure this is the right page for this but I wonder if we need a passage discussing the biological significance of Km. I think this would help people relate more to these numbers. For example, physiological substrate concentrations are often quite close to the Km. Different isozymes can have different Km values, depending on the location in a cell or tissue. This type of thing. What do you think? David D. (Talk) 22:04, 26 September 2006 (UTC)

Yes, I suppose we do need a "What the hell do all these numbers mean?" section. Perhaps as a sub-section in Single substrate reactions, which is where they are first introduced. TimVickers 22:14, 26 September 2006 (UTC)

Briggs-Haldane modification to the M-M scheme[edit]

Would like to a see a little on that. Some material here and cheers Shyamal 01:52, 27 September 2006 (UTC)

Paragraph on this added to end of Michaelis-Mentan section. TimVickers 14:50, 29 September 2006 (UTC)

What about Adair & Monod equations? And Koshland's? (allosterism) And why don't you explain how do we reach the inhibition equations?

Since these equations relate to allostery in general, not just enzyme kinetics, they would be best added to the page on cooperativity. I think deriving all the inhibition equations would take several pages and not add much to an article for the general reader. TimVickers 20:41, 19 October 2006 (UTC)

Sigmoidal curves with non-cooperative binding?[edit]

The article says: "Some enzymes produce a sigmoid v by [S] plot, which often indicates cooperative binding of substrate to the active site." Could non-cooperative binding with multiple binding sites also produce sigmoidal curves? In other words, do sigmoidal curves always necessitate a ligand binding to one site to affect the affinity of other sites? Is there a counter-example? Can non-cooperative binding cause threshold effects via sigmoidal activation? (it seems so based on the following article, but I am not sure: Suu 14:35, 26 January 2007 (UTC)

Substrate activation is a possibility in one active site, where ES2 is more active than ES. However, these two molecules of substrate must bind in different places, even if these are adjacent. However, I can envisage a model where an enzyme has two slowly-interconverting conformations with the active conformation being stabilised by substrate. I'll try to find if this has been observed. TimVickers 16:55, 26 January 2007 (UTC)

The effects of temperature and environment on enzyme kinetics[edit]

I haven't been able to read the whole article yet, but through skimming and searching I can't see any mention of the action of temperature on enzyme kinetics (e.g. exponential increase of activity then sudden denaturation, different optimums in coldblooded and warmblooded animals, thermophiles etc), and there also seem to be little on the effects of chemical factors (such as pH changes, different environments in various organs and organelles). The article is no doubt of a high quality, but these seem to be serious omissions for a featured article. They are mentioned briefly in the enzyme article, and I was expecting the main discussion of them to be here. Richard001 04:45, 31 July 2007 (UTC)

These are discussed briefly in Enzyme assay, but protein stability hasn't got much to do with enzyme kinetics. Temperature in particular is very badly described in these terms, since the "optimum" rate of an enzyme reaction is the product of two rates, the reaction rate and the denaturation rate. If you were to use an assay measuring activity for one second, it would give high activity at high temperatures, however if you were to use an assay measuring product formation over an hour, it would give you low activity at these temperatures. It is discussed in this paper in a bit more detail. Tim Vickers 16:02, 2 August 2007 (UTC)
Oh, I hadn't looked at enzyme assay. It basically covers the areas I'm talking about, but doesn't go into great detail. Where would be the best article to expand on these factors? Richard001 04:38, 4 August 2007 (UTC)
Enzyme assay I suppose, it isn't a particularly good article at the moment so your edits could improve it a great deal. Tim Vickers 14:39, 4 August 2007 (UTC)
True 06:31, 22 October 2007 (UTC)

Molarity is obsolete[edit]

A surprisingly long and vigorous discussion on a small point of nomenclature
The following discussion has been closed. Please do not modify it.

User:TimVickers said see talk, but went to my talk page instead and based his argument on a recent, disputed addition top the MoS by none other than User:TimVickers. See Wikipedia talk:Manual of Style#Units of measurement. Gene Nygaard 23:45, 22 October 2007 (UTC)

Here is what NIST has to say about it:

  • "The term molarity and the symbol M should no longer be used because they, too, are obsolete. One should use instead amount-of-substance concentration of B and such units as mol/dm3, kmol/m3, or mol/L. (A solution of, for example, 0.1 mol/dm3 was often called a 0.1 molar solution, denoted 0.1 M solution. The molarity of the solution was said to be 0.1 M.)"

NIST Special Publication 811, Guide for the Use of the International System of Units (SI), 1995, section 8.6.5[1]

Gene Nygaard 23:53, 22 October 2007 (UTC)

Could you explain why we should use a different unit of measurement than the units used in the current scientific literature on enzyme kinetics?
See for example:
    • Stroppolo ME, Falconi M, Caccuri AM, Desideri A (2001). "Superefficient enzymes". Cell. Mol. Life Sci. 58 (10): 1451–60. PMID 11693526. 
    • Miller BG, Wolfenden R (2002). "Catalytic proficiency: the unusual case of OMP decarboxylase". Annu. Rev. Biochem. 71: 847–85. PMID 12045113. 
    • Sievers A, Wolfenden R (2005). "The effective molarity of the substrate phosphoryl group in the transition state for yeast OMP decarboxylase". Bioorg. Chem. 33 (1): 45–52. PMID 15668182. 
    • Xia Z, Azurmendi HF, Mildvan AS (2005). "Transient state kinetic studies of the MutT-catalyzed nucleoside triphosphate pyrophosphohydrolase reaction". Biochemistry. 44 (46): 15334–44. PMID 16285737. 
I have not found a single publication that uses mol L-1 s-1 for this rate constant. Tim Vickers 23:58, 22 October 2007 (UTC)
For one thing, because we are not "scientific literature". We should be understandable to scientifically literate people, without them having to learn, especially when it comes to measurements, an arcane jargon peculiar to a specific field of endeavor. The interdisciplinary nature of the SI is just as important as its international nature. Gene Nygaard 00:15, 23 October 2007 (UTC)

It's not evident on this web page abstract, but according to the text visible in my Google search, this one does (in the form mol/(l s), which is the same thing in case anyone is unfamiliar with the superscript notation which I merely continued as it existed before):

  • A. G. Galstyan, "Kinetics and mechanism of liquid-phase catalytic ozonation of nitrotoluenes", Petroleum Chemistry, Volume 46, Number 5 / October, 2006

Gene Nygaard 00:22, 23 October 2007 (UTC)

I'll just cite a web link for this abstract,

  • "It was found that, in the temperature range 20–40°C, the rate constant of this reaction varies from 0.7 to 6.0 mol/(l s)."

Gene Nygaard 00:31, 23 October 2007 (UTC)

Here's a .pdf file for use in a class at Rowan University:

I would certainly hope that there are more and more teachers out there who follow the recommendations of the standards organizations. I remember how grateful I was ages ago when I had a college professor who insisted on using SI, relieving us of all the confusion of angstroms and ergs and the like. Too bad Wikipedia hasn't caught up to that yet, though it is pretty good in most areas. Gene Nygaard 00:41, 23 October 2007 (UTC)

Alright, so the worldwide authority on unit systems says don't use molarity. I don't think anyone I know has gotten that memo, because I see it all the time in publications and solution labels (commercial and my own). Molarity is clearly still in broad use...
That said, it's silly to argue over this. M == mol L-1. If someone puts "5 mM" in an article, an enterprising editor wouldn't be incorrect in changing the presentation to 5 mmol L-1, no information is technically lost and the amount is marginally clearer. I'd support a MoS recommendation that all molarity be presented in the more technically clear method suggested, but let's not get carried away here. — Scientizzle 00:46, 23 October 2007 (UTC)

The two are exactly the same and I think we should use the one that is more common. Searching on Google for "M s-1" enzyme returns 11,700 hits, while doing the same for "mol s-1" enzyme only returns 767. If we use a different set of units from everybody else this is just going to make things difficult for our readers. Let's just follow the literature. Tim Vickers 01:21, 23 October 2007 (UTC)

The way it reads now, with "mol L-1" linking to molarity seems a perfectly clear solution. I understand what you're saying, Tim, but this dispute is so esoteric it limits its importance. I wouldn't be philosophically opposed (though aesthetically wary) of presenting both nomenclatures as one might put both miles & kilometers in an article... — Scientizzle 15:23, 23 October 2007 (UTC)
But you are limiting yourself to the superscript format in your search, in the first place. In the second place, when you use two single letters, even if you separate them with a space, Google normally includes unspaced results. I wouldn't be surprised if you end up finding "ms" for milliseconds and "MS" for manuscript and whatever. And the hyphen isn't searched for in any case (it does the same thing as putting quotation marks around something, but I assume you were already doing an exact search anyway so it wouldn't have any effect whatsoever). Gene Nygaard 01:54, 23 October 2007 (UTC)
A Google search for the exact phrase "molarity for second" gets 17 hits, versus "moles per liter second" with 6 hits. Wow, a 2.8 to 1 ratio! Overwhelming evidence? Hardly.
Especially not when you add in the 66 hits for "moles per liter per second" and 23 hits for "moles per litre per second".
Then we need to get into cubic decimeters and the like too, and prefixes with the moles (for kmol/(m³·s) and the like). Get the idea? Gene Nygaard 02:06, 23 October 2007 (UTC)
However, if you look at what the people who actually do enzyme kinetics choose to use, we all use M. In searching through the recent literature I didn't find any instances of people actually using this new nomenclature. As Scientizzle said, if this was the recommendation, nobody got the memo. A system that is good enough for Annual reviews in Biochemistry should be good enough for us. Tim Vickers 16:01, 23 October 2007 (UTC)

Could someone please fix the terminology in question? Currently it reads: mol-1 L-1 s-1. Regardless of whether you use M or mol L-1, mol-1 L-1 is incorrect. To input on the discussion, I do not consider Google the best place to look for scientific articles. Pull out a journal like Biochemistry and read through it. I have yet to find an article that does not use the more conventional M in place of mol L-1. Be forewarned that a significant proportion of the scientific community will favor the use of M, in which case it can hardly be considered obsolete. BobertWABC 19:58, 26 October 2007 (UTC)

Yes, that addition was wrong. I've changed it back to M-1 s-1, but if people do want to convert this back to mol L-1 s-1 please don't simply revert, as this will take it back to the incorrect units. As you suggest, I had a look through Biochemistry. These are some of the 2007 abstracts I could find with a search for "rate s-1"


Linkage between Substrate Recognition and Catalysis during Cleavage of Sarcin/Ricin Loop RNA by Restrictocin
The Heme Pocket Geometry of Lucina pectinata Hemoglobin II Restricts Nitric Oxide and Peroxide Entry: Model of Ligand Control for the Design of a Stable Oxygen Carrier
Substrate Specificity Profiling and Identification of a New Class of Inhibitor for the Major Protease of the SARS Coronavirus
Enzymatic Catalysis of Proton Transfer at Carbon: Activation of Triosephosphate Isomerase by Phosphite Dianion
Kinetic Mechanism of Enterococcal Aminoglycoside Phosphotransferase 2' '-Ib

Journal of Biological Chemistry

The Lipocalin {alpha}1-Microglobulin Has Radical Scavenging Activity
Phenylalanine Biosynthesis in Arabidopsis thaliana
Inhibition of human dimethylarginine dimethylamionhydrolase-1 by S-nitroso-L-homocysteine and hydrogen peroxide: Analysis, quantification, and implications for hyperhomocysteinemia
Single Molecule Kinetic Analysis of Actin Filament Capping
Every single one uses the M-1 s-1 notation. Tim Vickers 19:10, 23 October 2007 (UTC)
If it is changed again (which I am not in favor of, being an enzymologist myself), make sure that it is changed to mol-1 L s-1, and not mol-1 L-1 s-1, as this is incorrect. mol-1 L-1 is not the same as M-1, mol-1 L is. BobertWABC 19:58, 26 October 2007 (UTC)
Well, in that case, sorry for messing that bit up. But here's one from Journal of the Brazilian Chemical Society[2]
  • "values for k1, k-1 and Keq are 0.28 mol-1 L s-1, ..."
No matter how many times Tim Vickers repeats claims on the order of "every single one", it isn't going to be true. Gene Nygaard 00:47, 24 October 2007 (UTC)
I am perfectly aware that if you desperately scrape through obscure journals you will find a few papers that use this notation. So far you have cited the Journal of the Brazilian Chemical Society and Petroleum Chemistry, neither of which have anything to do with enzyme kinetics. I have shown you what Biochemistry, The Journal of Biological Chemistry and Annual Review of Biochemistry use as their standard notation. Anybody with a good grasp of the subject will see the difference in sources here, I'm citing the top journals in biochemistry, you are citing obscure journals dealing with organic and inorganic chemistry. To be honest, this has me at a bit of a loss, since if you won't accept this absolutely clear evidence of standard modern biochemical usage I can't think what I could possibly produce that would convince you. Tim Vickers 01:29, 24 October 2007 (UTC)
Okay. So what's this in the Journal of Biological Chemistry, then. Is this the same quantity under discussion here in this abstract, expressed in L/mol-s?
Gene Nygaard 02:07, 26 October 2007 (UTC)
Besides that, remember that you are on Wikipedia now. It's not nice to denigrate a journal because it is Brazilian, and insist that we should take a USA-centric viewpoint. Gene Nygaard 02:14, 26 October 2007 (UTC)
Since you agree JBC is a reasonable journal, shall we just use the nomenclature that is most common in 2007 papers in JBC? Would you agree that would be a fair test of current usage? Tim Vickers 02:17, 26 October 2007 (UTC)
No. And furthermore, I don't even agree that testing for current usage is relevant. This isn't a biochemistry journal. This is a general-audience encyclopedia, and should be using the universal SI units familiar to people in many different fields of activity worldwide.
But your tacit admission that once again you have been caught in false claims of universality is accepted. Gene Nygaard 02:41, 26 October 2007 (UTC)
One use, especially in the journals you specifically pointed us to, of standard SI units (incl. those specifically declared acceptable for use with SI such as the liter) is enough to establish the fact that L/(mol·s) are in current use in the scientific literature. Professionals in the field should be familiar with them and should not have much difficulty understanding them. But, on the other hand, nobody outside the field has any need to be familiar with things that aren't even really units of measure, but are treated as if they were. Gene Nygaard 03:01, 26 October 2007 (UTC)
Furthermore, the fact that one of your faves, the The Journal of Biochemistry, didn't even properly express the units doesn't speak very well for it. According to normal rules, division and multiplication proceed from left to right, unless grouped with parentheses. So their "L/mol-s" would be "mol−1 L s" in the exponent notation used in this article, rather than the proper "mol−1 L s−1". Pretty strange that a stickler for accuracy like you would let that slide. Gene Nygaard 03:09, 26 October 2007 (UTC)

Hey Gene, should we be woried that no one uses Pascals? I find it incomprehensible that wikipedia is still using atmospheres, bars, mmHg AND pounds per square inch! David D. (Talk) 03:16, 26 October 2007 (UTC)

So despite that fact that you have spent the last two days arguing that mol−1 L s−1 is the current usage, when it becomes obvious to you that it is not, you switch to arguing that current usage is irrelevant. However, I am willing to abide with consensus here and to avoid any more wasted time let's just have a straw poll and abide with the result. Tim Vickers 03:58, 26 October 2007 (UTC)
Well, David, the people who use "Pascals" usually get it corrected, eventually, to "pascals". And those who use the other non-SI units usually get a conversion to SI units added. That's the minimum we need here, if we are going to include what are not only non-SI but also non-units, we need a conversion to SI units along with them. Gene Nygaard 13:59, 26 October 2007 (UTC)
Well Gene, being a smart arse isn't going to win you any supporters, is it? David D. (Talk) 04:18, 29 October 2007 (UTC)
First off, TimVickers did in no way "denigrate" a journal because it was Brazilian. He pointed out that the journal was not one related to biochemistry (which it wasn't). The journal JBC and Biochemistry may be published in USA, but are not USA-centric. Journal articles are published in format which would be accepted world-wide. To suggest that the two most important journals in the field are not up to par pits you against nearly the entire field of biochemistry and biochemists. I too agree that the poll is not the proper way to go, considering that the qualifications of those that cast their vote cannot be known. Your argument is that we must use accepted notation because this is a general encyclopedia and should be understood by the populace. In that regards, it would be unjust for someone searching the encyclopedia for a better understanding of a topic only be faced with terminology not in current use in the field. It would in no way be helpful to them. The only way to resolve the issue at hand (that I see) is to use "proper" SI units, followed with the remark "or more commonly..." Would this be satisfactory? This way someone coming from a non-biochemical background will automatically appreciate the standard unit usage, but will also be aware that they will most likely not encounter it in the biochemical field.BobertWABC 15:18, 26 October 2007 (UTC)
An excellent proposal Bobert, I have added the SI units (mol dm-3 s-1, as recommended by the Nomenclature Committee of the International Union of Biochemistry) and the comment on the usual units. Hopefully that will be acceptable to everybody. Tim Vickers 16:25, 26 October 2007 (UTC)
Sorry, Tim. One more thing. Should it not be mol-1 dm3 s-1? That would be M-1 s-1. As it is, what is shown is the equivalent of M s-1. BobertWABC 19:58, 26 October 2007 (UTC)
No problem, you're quite right. I'm following Nomenclature Committee of the International Union of Biochemistry (NC-IUB) - Symbolism and Terminology in Enzyme Kinetics. This seems the most authoritative source possible. As a comment, I note that they state in their Summary of recommended symbols: "Although for brevity and convenience all volumes are expressed in dm3, in all cases dm3 may be replaced identically with L or l (liter), and amount-of-substance concentrations may be expressed in M (molar), which is identical with mol dm-3" Tim Vickers 20:06, 26 October 2007 (UTC)
See, now it comes out that, despite all your claims about what is used in that field, even your own professional standards organization recommends the SI usage. QED. Gene Nygaard 23:14, 26 October 2007 (UTC)
If you are still around, and still using M, 10 years from now, will that be a badge identifying you as a true dinosaur in the field? Gene Nygaard 23:26, 26 October 2007 (UTC)
As I quoted, they say that non-SI units like L and M are perfectly acceptable in all cases, but using the correct SI units of dm3 mol-1 s-1 appeared a good compromise. Thank you for being so reasonable and co-operative. Tim Vickers 23:27, 26 October 2007 (UTC)

FYI The most recent edition of the major international Biochemistry textbooks ((Voet, Lehninger, Garret & Grisham) all use M-1 s-1 format. All of my previous research articles have also used the same format. Not sure why there is a desire to change it, since it is the most prevalent and commonly used form.

"We should be understandable to scientifically literate people, without them having to learn, especially when it comes to measurements, an arcane jargon peculiar to a specific field of endeavor."

The concept of Molarity (M) is taught in high school Chemistry and once again in freshman level Chemistry, so calling it arcane jargon is specious. To me M-1 s-1 is more accessible of a unit that mol-1 L d-1, people that know what a mole is, remember what molarity is. If you expect them to think that mol-1 L is the same as M-1 on a first read through, I think you are mistaken. if this article is for the masses then lets go back to the unit that the majority use Hichris 21:18, 8 November 2007 (UTC)

Straw poll[edit]

M−1 s−1

  1. Tim Vickers 03:58, 26 October 2007 (UTC)
  2. -Biochem student in Ann Arbor, MI71.238.71.180 18:13, 2 December 2007 (UTC)
  3. -M.Sc. chem student, McGill. (talk) 19:35, 7 August 2008 (UTC)

mol−1 L s−1

Lack of foundation, object to relevance and phrasing and choices and much more[edit]

  1. Gene Nygaard 13:55, 26 October 2007 (UTC) It has no bearing on what we include, we are not limited to either/or choices (this isn't the article's name with only one slot available for it), unusual uses even if done need to be explained even if widely known ones such as the mole do not, it presumes wrongly that we have decided that we should use a superscript format, one of the advantages about the superscript format is that the order won't affect the validity of the expression, and a whole host of other problems. And polling is evil.
    Build a proper foundation. Don't hatch up some poorly devised poll, and see WP:POINT. Gene Nygaard 13:55, 26 October 2007 (UTC)
I like a good poll. It seems if one is interested enough to read this far, a poll can be a better indicator of the current consensus than just another comment that makes this discussion even harder to read. 18:23, 2 December 2007 (UTC)


I would like to point out that in the current version of the International Union of Biochemistry and Molecular Biology's nomenclature recommendations ( -> Publications -> Biochemical Nomenclature -> Nomenclature Website -> ( -> Enzyme Kinetics -> 13. Summary of recommended symbols) allows for the use of M (molar):

"Although for brevity and convenience all volumes are expressed in dm3, in all cases dm3 may be replaced identically with L or l (liter), and amount-of-substance concentrations may be expressed in M (molar), which is identical with mol dm-3. Both L and M may be used as primary units for forming multiples and submultiples such as mL, [mu]M, etc." [3]

That is to say, the recommendations of an international body writing on the specific point at hand differ from the recommendations of a standards body of a particular country, writing about the topic in generalities. -- 17:03, 6 December 2007 (UTC)

Random-order ternary-complex mechanism diagram[edit]

I believe the arrows in the second half of the diagram are going the wrong direction - P and Q are leaving the complex, not being added, so the arrows should be pointing away from the hexagonal pathway.IMKatgrrl (talk) 11:01, 23 October 2009 (UTC)

I believe so too, feel free to change it. It is still clear what is meant but it would be nicer if P and Q are leaving the complex. Greetings --hroest 12:08, 23 October 2009 (UTC)
Good point! Tim Vickers (talk) 16:09, 23 October 2009 (UTC)

Confusing picture[edit]

I sincerely apologize if I am being stupid, but this picture, which appears in the first section after the lead in the article, makes very little sense to me. If I understand correctly, whenever the article talks about the rate of reaction for a given concentration of substrate, it means the instantaneous or initial rate. So I take "at relatively high substrate concentrations, the reaction rate asymptotically approaches the theoretical maximum; the enzyme active sites are almost all occupied and the reaction rate is determined by the intrinsic turnover rate of the enzyme" to mean that if you've got very concentrated substrate then the enzyme will just eat away at the substrate, and the reaction will go at pretty much the same speed, since it was at the maximum already, but then after a while the rate will drop as the substrate is depleted. The figure, on the other hand, appears to bear no relevance to the caption, showing enzymes making ... more and more substrate over time? Please explain. Leonxlin (talk) 04:14, 18 August 2011 (UTC)

It's not meant to represent a change over time. It just shows what happens under different concentrations of substrates. Once all the enzymes are occupied, adding substrate has no more effect. (Approximately - in practice there is always a binding equilibrium and there are thus always a few empty places, the number of which decrease depending on how quickly the substrate can reach them). Probably the green arrows were a bad idea - I'd suggest editing the figure to take them out. Wnt (talk) 22:01, 4 September 2011 (UTC)
I took a stab at rewriting the figure legend.[4] Wnt (talk) 22:23, 4 September 2011 (UTC)

Too concentrated on Lineweaver-Burk plot?[edit]

Under "Linear plots of the Michaelis–Menten equation" the article seems to be too focused on Lineweaver-Burk, which is probably the worst of all the plots mentioned. Would it be worth changing this to Eadie-Hofstee or Hanes-Woolf, or just removing the focus on any one plot?

Esotera (talk) 10:57, 4 January 2012 (UTC)

Agree it should be changed. Who ever maintains this page I would recommend you use Lineweaver-Burk as an example of how not to analyse kinetic data. Rhodydog (talk) 00:29, 19 March 2013 (UTC)

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The meaning of Km in the section about "General principles"[edit]

The use of the word "quickly" in the sentence "The two most important kinetic properties of an enzyme are how quickly the enzyme becomes saturated with a particular substrate, and the maximum rate it can achieve." (Enzyme kinetics#General_principles) is very misleading because it seems to relate to time, whereas the MM model describes steady-state kinetics... What about "how easily it is saturated..." instead? Lewisiscrazy (talk) 09:17, 21 January 2018 (UTC)

Done --Lewisiscrazy (talk) 06:12, 20 March 2018 (UTC)

Adding a subsection about reversible catalysis?[edit]

I think it would be useful to add a subsection entitled "Reversible catalysis and the Haldane equation" in the section about Single substrate reactions. I have worked on this draft, what do you think? can somebody contribute? Lewisiscrazy (talk) 15:41, 21 January 2018 (UTC)

Added: --Lewisiscrazy (talk) 14:32, 11 February 2018 (UTC)
Check out WP:NOTTEXTBOOK. Wikipedia presents knowledge, but does not explain it. That is the encyclopedic style that can be subtle to grasp. Sections that begin "We consider the case of .." are in appropriate. --Smokefoot (talk) 13:08, 8 April 2018 (UTC)