Abstract
Enolpyruvyl shikimate-3-phosphate synthase (EC
2.5.1.19) was purified to near homogeneity (~90% purity)
from Klebsiella pneumoniae. Glyphosate, a herbicide, competitively inhibits with phosphoenolpyruvate (PEP) with K{
—
10™5 M. An analogue of shikimate 3-phosphate, 4,5-dideoxyshikimate 3-phosphate (ddS3P), competitively inhibits
with shikimate 3-phosphate with K{ =
10~2 M. The enzyme
is inactivated by 3-bromopyruvate. 1/2 for inactivation is
approximately 5 min at 0.15 mM 3-bromopyruvate. PEP
protects against inactivation by 3-bromopyruvate, while ddS3P
alone has no effect on the rate of inactivation. The protective
effect of PEP is enhanced approximately 16-fold in the
presence of ddS3P. The enzyme catalyzes exchange of solvent
3H into PEP in the presence of ddS3P but not in its absence.