Talk:Enzyme catalysis

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Schiff base catalysis[edit]

Would this mention belong better in the acid/base catalysis section? I wouldnt know.... - Zephyris Talk 00:16, 20 February 2007 (UTC)

No it is a form of covalent catalysis, despite the name, and is in the correct section. TimVickers 00:22, 20 February 2007 (UTC)

Free energy vs. activation free energy[edit]

In the section about induced fit catalysis care should be taken to distinguish between the free energy of reactionand(ΔG)amd the activation free energy (ΔG). The sentence "...have been evolutionarily chosen to minimize the ΔG of the reaction" e.g. is misleading, it should read ΔG 555+ instead. - Marsipan Talk 2:27, 24 September 2007 (GMT)

In the introduction it says:

The reduction of activation energy (ΔG) increases the number of reactant molecules with enough energy to reach the activation energy and form the product.

This confuses me. Is it trying to say that change in free energy (ΔG)=activation energy? Am I right in saying that it should be changed to: "The reduction of activation energy (Ea) increases the number of reactant molecules with sufficient energy (>Ea) to form the product"? --158.39.91.162 (talk) 10:38, 7 October 2008 (UTC)

The first figure in this article is also incorrect. E + P should be at a lower G than EP. —Preceding unsigned comment added by 192.52.218.45 (talk) 14:01, 4 March 2009 (UTC)

I've always seen the diagram as presented. That is, E+P is at a higher free energy state than EP (due to decreased entropy from product solvation? I would think the enthalpic difference would generally be negligable, since water and amino acid residue side chains can hydrogen bond equally well and the high dielectric constant of water washes out any coulombic interaction differences). The converse is thus true for reactant binding. Pdcook (talk) 21:11, 29 September 2009 (UTC)

The relative energy levels are depending on the particular reaction. It can well be that EP is lower. Most of times we do not honestly know anything about it. This is just a modell, no more. Also, I disagree with the "lowering of activation energy" which is naive. The reaction will most of times will practically not take place at all without catalyst. This is either due to the imense accelaration at temperatures near ambient by enzymes if the reaction is at all taking place without it or the reaction path is only feasible with the enzyme. Maybe we can get rid of these false concepts here? LGreiner (talk) 08:54, 23 February 2015 (UTC)

Covalent Catalysis[edit]

What about cofactors such as pyridoxal phosphate or thiamine pyrophosphate? Perhaps they should be mentioned in this section. Pdcook (talk) 20:21, 11 September 2009 (UTC)

Well, since no one seems to be saying no, I'll add a couple of examples. Feel free to improve my additions. Pdcook (talk) 17:13, 30 September 2009 (UTC)

Fix the first sentence![edit]

Seriously? "Enzyme catalysis is the catalysis of chemical reactions by specialized proteins known as enzymes."

This is basically one step away from Enzyme catalysis is catalysis by enzymes. —Preceding unsigned comment added by 64.203.157.127 (talk) 01:22, 11 October 2010 (UTC)

I totally agree: trivial definition! עבד יהוה talk

I've taken a stab at revising the opening sentence. See if this is a bit better, albeit wordier. --User:Ceyockey (talk to me) 16:16, 17 January 2015 (UTC)
Good work Ceyockey. I've further edited it a little to define catalysis and simplify wording by splitting into two sentences - sentence 1 in the part that is true for all enzymes, sentence two is what's true for only some enzymes (e.g. cofactor use). Let me know what you think! T.Shafee(Evo﹠Evo)talk 23:59, 17 January 2015 (UTC)

Equilibrium[edit]

There seems to be a common misconception that enzymes can actually alter the equilibrium of a reaction. Since this is more than just a simple, No They Can't statement (if you couple it with ATP, a non-catalytic reagent, you actually can affect equilibrium), I thought I would put it into talk so people could work hard to arrive at a correct, but not confusing, analysis. -- עבד יהוה talk 16:59, 3 April 2013 (UTC)

You are right.  This sentence is incorrect:

The acid catalyst itself (AH) only contributes to the rate acceleration by shifting the chemical equilibrium between solvent S and AH in favor of the SH+ species. — Preceding unsigned comment added by 71.191.189.239 (talk) 14:27, 5 May 2013 (UTC)