Enzymes that exploit imines – one way or the other

Stereochemistry of the Enolization of Scytalone by Scytalone Dehydratase

“…It is worth comparing the results herein with those for the two biochemically distinct types of dehydroquinase, which are well-studied enzymes that also carry out the dehydration of a ring β-hydroxyketone ( − ). The type I dehydroquinase shares with SD the stereochemical course of a syn elimination.…”

The biosynthesis of shikimate metabolites (1998)

“…63 The resulting NMR spectra of neoantimycin showed the specific and efficient incorporation of the methyl group of propionate and the methyl group of methionine into the C-12 and C-13 methyl groups respectively. No significant specific incorporation of the 13 C isotope was seen following the sodium [2- 13 C]acetate feeding experiment. A feeding experiment utilising [(S)-1 H, 2 H, 3 oxidation of neoantimycin to excise C-11 and C-13 as acetic acid followed by configurational analysis showed that as expected the stereochemistry of the methyl group derived from methionine is inverted during the transfer to C-11 of the metabolite.…”

“…The role of the conserved His-143 residue in the mechanism of catalysis of type I dehydroquinase from E. coli has been probed by use of 2D 1 H and 13 C NMR spectroscopy. 9 The results of pH titration experiments with isotopically enriched wild type DHQase (via use of [2-13 C]histidine) and a His-143-Ala mutant indicated that, at pH values corresponding to optimal enzyme activity (pH > 7), His-143 resides in its unprotonated form.…”

“…An excellent overview of the nature and catalytic mechanism of both type I and II 3-dehydroquinase has been published which includes discussion on the rational design of mechanistic inhibitors of these enzymes. 13…”