Lysine 183 is the general base in the 6-phosphogluconate dehydrogenase-catalyzed reaction

Citation
Z. Lei et al., Lysine 183 is the general base in the 6-phosphogluconate dehydrogenase-catalyzed reaction, BIOCHEM, 38(35), 1999, pp. 11231-11238
Citations number
35
Categorie Soggetti
Biochemistry & Biophysics
Journal title
BIOCHEMISTRY
ISSN journal
00062960 → ACNP
Volume
38
Issue
35
Year of publication
1999
Pages
11231 - 11238
Database
ISI
SICI code
0006-2960(19990831)38:35<11231:L1ITGB>2.0.ZU;2-J
Abstract
Site-directed mutagenesis was used to change K183 of sheep liver B-phosphog luconate dehydrogenase to A, E, H, C, Q, R, and M to probe its possible rol e as a general base catalyst. Each of the mutant proteins was characterized with respect to its kinetic parameters at pH 7 and the pH dependence of ki netic parameters for the K183R mutant enzyme. The only mutant enzyme that g ives a significant amount of catalysis is the K183R mutant, and the extent of catalysis is decreased by about 3 orders of magnitude; the general base pK is perturbed to a pH value of >9. All other mutant enzymes exhibit rates that are decreased by about 4 orders of magnitude compared to that of the wild-type enzyme. Data are consistent with the general base function of K18 3.