Hyun Ik Park and Li-June Ming*
Department of Chemistry and Institute for Biomolecular Science
University of South Florida
Tampa, Florida 33620-5250
Abstract
Although tetrahedral phospho-moieties often serve as transition-state
analogues in peptide hydrolysis, we found that bis-p-nitrophenylphosphate
(BNPP) can be effectively hydrolyzed into nitrophenylphosphate and p-nitrophenol
by a di-Zn aminopeptidase from Streptomyces griseus (sAP). This di-Zn
enzyme gives a remarkable specific activity 33.7 nmol min–1
mg–1 toward the hydrolysis of 1 mM BNPP
comparable to some native phosphodiesterases, and a second rate constant
kcat/Km = 100 M–1s–1
that is >106 times superior to several
Zn2+-containing chemical models. The rate
enhancement of BNPP hydrolysis by sAP is about 1010
when compared with the first order rate constant of BNPP auto-hydrolysis.
This study indicates that sAP can serve as a novel dinuclear model to provide
further insight into dinuclear hydrolysis in chemical and biological systems.