On Thursday, May 7, 1998 at 2:00:00 AM UTC-5, Dennison wrote:
> Does anyone know how thioester bonds would react to the conditions
> typically used in reducing (Laemmli) SDS-PAGE? Is the pH per se high
> enough to break them?
> Any info and refs would be appreciated.
Thioesters are formed transiently during decarboxylase reactions. The Breslow reaction scheme for pyruvate decarboxylase is incorrect; this actually involves the ring‐opening of thiamine, exposing an internal thiol which attacks the carbonyl carbon or pyruvate.
The resulting two carbon unit is then shifted to another thiol, this time the lipoic acid prosthetic group. It is then transferred to coenzyme A — yet another thiol.
So the thiol could perhaps be seen by it's ability to form low‐energy carbon bonds, useful for shuttling acyl and acetyl groups during metabolism. As previously mentioned by Rob, vide infra, these thiol molecules would be more likely to release their substrates in reducing conditions — perhaps yet another way in which the cell controls its oxidation rate.