Transient kinetic analysis of the interaction of L-serine with Escherichia coli D-3-phosphoglycerate dehydrogenase reveals the mechanism of V-type regulation and the order of effector binding.

ABSTRACT: Pre-steady state stopped-flow analysis of Escherichia coli d-3-phosphoglycerate dehydrogenase (PGDH) reveals that the physiological inhibitor, l-serine, exerts its effect on at least two steps in the kinetic mechanism, but to very different degrees. First, there is a small but significant effect on the dissociation constant of NADH, the first substrate to bind in the ordered mechanism. The effect of serine is mainly on the binding off rate, increasing the K(d) to 5 and 23 muM from 0.6 and 9 muM, respectively, for the two sets of sites in the enzyme. A more profound effect is seen after the second substrate is added. Serine reduces the amplitude of the signal without a significant effect on the observed rate constants for binding. The serine concentration that reduces the amplitude by 50% i

SUBMITTER: Burton RL 

PROVIDER: S-EPMC2797576 | biostudies-literature | 2009 Dec

REPOSITORIES: biostudies-literature