Phosphatases are diverse groups of enzymes that deserve special attention because of their significant roles in organic phosphorus (OP) mineralization to inorganic available forms (Pi). This work 1) compared the catal...Phosphatases are diverse groups of enzymes that deserve special attention because of their significant roles in organic phosphorus (OP) mineralization to inorganic available forms (Pi). This work 1) compared the catalytic potentials of commercially acid phosphatase from wheat germ, sweet potato, and potato, and alkaline phosphatase from E. coli;2) demonstrated that the rate of hydrolysis, catalytic efficiency, thermal stability, and optimal pH of these enzymes depended on enzyme sources and the stereochemical or stereoisomeric structures of the substrates;3) revealed that both acid and alkaline phosphatases exhibited broad range of substrate hydrolysis with high affinity for p-nitrophenyl phosphate bis (cyclohexylammonium) than the widely used p-nitrophenyl phosphate disodium hexahydrate for phosphatase assay. Sweet potato had relatively higher reaction kinetics (Vmax, Km, Kcat, Kcat/Km) values with most substrates tested. The order of catalytic activity was in the order: sweet potato > wheat germ > potato, while the order of substrate hydrolyzed was: PNPBC > PNP > PNP2A2E > DG6P2Na > DG6PNa > Bis-PNP > phytate. The optimum pH for the acid phosphatase was observed to be 5.0. Generally, the activity of alkaline phosphatase was similar to that of acid phosphatase with optimal pH between 10 and 13, depending on the substrates. Knowledge derived from this work would be helpful in enzyme catalysis in soils and water environments.展开更多
The effect of acute E.coli challenge on the anti-disease activity of scallops Argopecten irradians is examined.The treatments of scallop from which hemolymph samples were taken for study included(1)control scallops,(2...The effect of acute E.coli challenge on the anti-disease activity of scallops Argopecten irradians is examined.The treatments of scallop from which hemolymph samples were taken for study included(1)control scallops,(2)sham-injected scallops,(3)PSW-injected scallops and (4)E.coli-injected scallops.From the beginning,the anti-disease activites of scallops are determined at 12 hr and 24hr.The concentrations of circulating hemocytes,the total serum protein concentrations and the activities of alkaline phosphatase,acid phosphatase and superoxide dismutase in the scallops Argopecten irradians are determined.Injection with E.coli results in a significant elevation in the concentration of circulating hemocytes and in the alkaline phosphatase activity and a significant decline in the total serum protein concentration and in the superoxide dismutase activity at 24 hr postchallenge.It shows that metabolism of bay scallop is expedited to adopt the challenge.展开更多
文摘Phosphatases are diverse groups of enzymes that deserve special attention because of their significant roles in organic phosphorus (OP) mineralization to inorganic available forms (Pi). This work 1) compared the catalytic potentials of commercially acid phosphatase from wheat germ, sweet potato, and potato, and alkaline phosphatase from E. coli;2) demonstrated that the rate of hydrolysis, catalytic efficiency, thermal stability, and optimal pH of these enzymes depended on enzyme sources and the stereochemical or stereoisomeric structures of the substrates;3) revealed that both acid and alkaline phosphatases exhibited broad range of substrate hydrolysis with high affinity for p-nitrophenyl phosphate bis (cyclohexylammonium) than the widely used p-nitrophenyl phosphate disodium hexahydrate for phosphatase assay. Sweet potato had relatively higher reaction kinetics (Vmax, Km, Kcat, Kcat/Km) values with most substrates tested. The order of catalytic activity was in the order: sweet potato > wheat germ > potato, while the order of substrate hydrolyzed was: PNPBC > PNP > PNP2A2E > DG6P2Na > DG6PNa > Bis-PNP > phytate. The optimum pH for the acid phosphatase was observed to be 5.0. Generally, the activity of alkaline phosphatase was similar to that of acid phosphatase with optimal pH between 10 and 13, depending on the substrates. Knowledge derived from this work would be helpful in enzyme catalysis in soils and water environments.
基金Funded by Projects under the Major State Basic Research Developmet Program(G1999012010)
文摘The effect of acute E.coli challenge on the anti-disease activity of scallops Argopecten irradians is examined.The treatments of scallop from which hemolymph samples were taken for study included(1)control scallops,(2)sham-injected scallops,(3)PSW-injected scallops and (4)E.coli-injected scallops.From the beginning,the anti-disease activites of scallops are determined at 12 hr and 24hr.The concentrations of circulating hemocytes,the total serum protein concentrations and the activities of alkaline phosphatase,acid phosphatase and superoxide dismutase in the scallops Argopecten irradians are determined.Injection with E.coli results in a significant elevation in the concentration of circulating hemocytes and in the alkaline phosphatase activity and a significant decline in the total serum protein concentration and in the superoxide dismutase activity at 24 hr postchallenge.It shows that metabolism of bay scallop is expedited to adopt the challenge.
