Catalytic properties of the PepQ prolidase from Escherichia coli.
The PepQ prolidase from Escherichia coli catalyzes the hydrolysis of dipeptide substrates with a proline residue at the C-terminus. The pepQ gene has been cloned, overexpressed, and the enzyme purified to homogeneity. The k(cat) and k(cat)/K(m) values for the hydrolysis of Met-Pro are 109 s(-1) and 8.4 x 10(5)M(-1)s(-1), respectively. The enzyme also catalyzes the stereoselective hydrolysis of organophosphate triesters and organophosphonate diesters. A series of 16 organophosphate triesters with a p-nitrophenyl leaving group were assessed as substrates for PepQ. The S(P)-enantiomer of methyl phenyl p-nitrophenyl phosphate was hydrolyzed with a k(cat) of 36 min(-1) and a k(cat)/K(m) of 710 M(-1)s(-1). The corresponding R(P)-enantiomer was hydrolyzed more slowly with a k(cat) of 0.4 min(-1) and a k(cat)/K(m) of 11 M(-1)s(-1). The PepQ prolidase can be utilized for the kinetic resolution of racemic phosphate esters. The PepQ prolidase was shown to hydrolyze the p-nitrophenyl analogs of the nerve agents GB (sarin), GD (soman), GF, and VX.
Park
Min-Sun
MS
Department of Chemistry, P.O. Box 30012, Texas A&M University, College Station, TX 77842-3012, USA.
Hill
Craig M
CM
Li
Yingchun
Y
Hardy
R Kristoffer
RK
Khanna
Hemant
H
Khang
Yong-Ho
YH
Raushel
Frank M
FM
D001483:Base Sequence; D002384:Catalysis; D003001:Cloning, Molecular; D017931:DNA Primers; D004150:Dipeptidases / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D005798:Genes, Bacterial; D006868:Hydrolysis
D017931:DNA Primers; D004150:Dipeptidases; C022449:proline dipeptidase