Activities | Families | Sequences | Fold types | References | Help
B6db references: 7766176.

type Journal Article
authors Iwamoto, R.; Taniki, H.; Koishi, J.; Nakura, S.
title D-glucosaminate aldolase activity of D-glucosaminate dehydratase from Pseudomonas fluorescens and its requirement for Mn2+ ion
journal Biosci Biotechnol Biochem
sel selected
ui 7766176
year (1995)
volume 59
number 3
pages 408-11
keywords Aldehyde-Lyases/isolation & purification/*metabolism
abstract When D-glucosaminate dehydratase (GADH) was incubated with D- glucosaminate (GlcNA) in veronal buffer (VB; 0.01 M, pH 8.0), GlcNA was converted stoichiometrically to glyceraldehyde, pyruvate, and ammonia (aldolase reaction A). This reaction occurred in addition to the dehydratase reaction (conversion of GlcNA to 2-keto-3-deoxy-D-gluconate and ammonia: alpha,beta-elimination reaction, B). The ratio of the activities (A:B) was about 1:4. However, in potassium phosphate buffer (KPB; 0.04 M, pH 8.0), the aldolase reaction was inhibited to 3-4% of that in VB, and also inhibited by various derivatives of glycerol, in particular, glycerol-3-phosphate (glycerol-3-P) and glyceraldehyde-3- phosphate (glyceraldehyde-3-P) in VB. The native enzyme was inhibited by incubation with 0.1 M EDTA, and the activity was restored by incubation of the EDTA-treated enzyme with (Mn2+ + pyridoxal 5'- phosphate (PLP)). When the EDTA-treated enzyme was incubated with (Mn2+ + PLP + glycerol-3-P), the activity of reaction B increased to 131% but that of reaction A decreased to 21%. These results suggested that Mn2+, PLP, and the phosphate group of glycerol-3-P are involved in formation of the active enzyme. In the case of the aldolase reaction, Mn2+ ion, which might be essential for the reaction, is chelated by the phosphate group of glycerol-3-P with resultant inhibition of the aldolase reaction.
last changed 2009/06/26 10:43

B6db references