Use of inhibitors to study reactions catalyzed by enzymes requiring pyridoxal phosphate as coenzyme

Citation
B. Adams et al., Use of inhibitors to study reactions catalyzed by enzymes requiring pyridoxal phosphate as coenzyme, PUR A CHEM, 72(3), 2000, pp. 373-384
Citations number
32
Categorie Soggetti
Chemistry
Journal title
PURE AND APPLIED CHEMISTRY
ISSN journal
00334545 → ACNP
Volume
72
Issue
3
Year of publication
2000
Pages
373 - 384
Database
ISI
SICI code
0033-4545(200003)72:3<373:UOITSR>2.0.ZU;2-9
Abstract
The stereochemistry of a variety of pyridoxal phosphate-mediated enzymic re actions has been studied using enzyme inhibitors that are stereospecificall y labeled in the beta-position with deuterium. A versatile synthesis has be en developed to prepare a wide variety of stereospecifically labeled D- and L-amino acids and inhibitors. Investigation of the "turnover" of beta-chlo ro-D-alanine and D- and L-serine-O-sulfate by D-amino acid aminotransferase and L-aspartate aminotransferase respectively has shown that reaction with in the active site of the former enzyme occurs with retention of stereochem istry. Although L-aspartate aminotransferase is an enzyme of the alpha-fami ly, when it was incubated with beta-chloro-L-alanine in the presence of 2-m ercaptoethanol, beta-substitution occurred. This was shown to involve reten tion of stereochemistry, an outcome typical of reactions catalyzed by enzym es of the beta-family that have little or no homology with enzymes of the a lpha-family. Formation of the "Schnackerz intermediate" has been studied as has the D-amino acid oxidase catalyzed reaction of the naturally occurring inhibitor D-propargylglycine.