Talk:Aucubin
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Major Errors in Biosynthetic Diagram
[edit]The diagram for the biosynthesis (i.e. this http://en.wikipedia.org/wiki/File:Acubinbiosynthesisscheme.PNG) is absolutely riddled with inaccuracies and even biochemical impossibilities. Even in just glancing at it one can see issues like:
- on the second line where the lactol ring closes this is shown as a reduction with NADH. This closier though is a tuatomerization, so it is redox neutral and requires neither an oxidant nor a reductant (it may not even need a catalyst though that can't be discerned without experimentation).
- Depending on the stereochemistry in 8-epi-iridotrial the concerted mechanism of cyclization may not be physically possible. See here for a brief discussion: http://www.nature.com/nature/journal/v492/n7427/full/nature11692.html
Things get worse if this is trying to depict all the steps.
- For instance it shows the Geranyl Cation going strait to 10-hydroxygeraniol. That is two steps, the first step is a terpene sythase (or pyrophosphate hydrolase), and the second step is p450, this are probably not even located in the same organelles within the cell. Also the proper nomenclature there is 8-hydroxygeraniol. IUPAC nomenclature requires the lower numbering always go to the higher priorety group, which will always be the methyl group with the alcohol on it here, so whichever terminal methyl group it is on it is still 8-hydroxygeraniol and never 10-hydroxygeraniol (admittedly many peer reviewed papers make this mistake, but that is no reason to help propigate it further.) Same goes for the subsequent "10-hydroxynerol" (should again be 8-hydroxynerol)
- Getting to that trialdehyde on the right most position of the second line will require at least two steps, a p450 and then an oxidoreductase (if not multiple oxido reductases). This step(s) will not be just NAD+, it will require 1O2, 1NADH, and 3NAD+ (so net 2NAD+)
There is probably a lot more but I didn't really even have time to comment as much as I have, I just was stopped in my tracks and couldn't let such a problematic diagram stand uncriticized.149.155.222.31 (talk) 21:20, 26 June 2014 (UTC)149.155.222.31 (talk) 21:28, 26 June 2014 (UTC)