Specific detection and properties of enzyme hydrolyzing phosphonate ester in serum.
An enzyme capable of hydrolyzing 4-methylumbelliferyl phenylphosphonate to 4-methylumbelliferone and phenylphosphonic acid has been detected in human serum. It has a Km value of 1.72 x 10(-4) mol/L, has an optimum pH of 8.8-9.1 in Tris buffer, and shows maximum activity at 60 degrees C (30 min). The enzymic activity can be inhibited by Na3PO4, EDTA, and cysteine. We saw no effect of CuSO4, adenosine, thymidine, NaN3, diethyl p-nitrophenyl phosphate, p-chloromercuribenzoate, isopropyl fluorophosphate, or eserine on the enzymic activity. The enzyme cannot hydrolyze substrates of phosphodiesterase I or alkaline phosphatase. The enzyme is considered a phosphonate esterase.
Han
G Y
GY
Jinan Institute of Military Medicine, ShanDong, People's Republic of China.
Fan
X H
XH
Jin
X B
XB
Wang
D P
DP
D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D004795:Enzyme Stability; D004950:Esterases / Q000037:antagonists & inhibitors / Q000097:blood*; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006923:Hymecromone / Q000378:metabolism; D007223:Infant; D007700:Kinetics; D063065:Organophosphonates / Q000378:metabolism*; D009943:Organophosphorus Compounds / Q000378:metabolism; D011247:Pregnancy; D012016:Reference Values; D013379:Substrate Specificity; D013696:Temperature
D063065:Organophosphonates; D009943:Organophosphorus Compounds; D006923:Hymecromone; C023604:phenylphosphonic acid; D004950:Esterases