<正> E.coli L-asparaginase,an antitumor enzyme,was chemically modified with N,O-carboxymethyl chitosan to lower its artigenicity and increase its plasma half-life.The results showed that the modified L-asparagin...<正> E.coli L-asparaginase,an antitumor enzyme,was chemically modified with N,O-carboxymethyl chitosan to lower its artigenicity and increase its plasma half-life.The results showed that the modified L-asparaginase has almost the same apparent Km value as that of native enzyme.The modified L-asparaginase also showed a higher protease stability against trypsin and a-chymotrypsin.After being modified,the enzyme exhibited the complete loss of antigenicity towards antiasparaginase serum.In addition,the higher the molecular weight of modifying reagents,the better the effects on reduction of antigenicity.When tested in vivo,the plasma half-life of the modified enzyme (t1/2=40 h) was over 33 times longer than that of the native enzyme (t1/2=1.2 h).展开更多
<正> Synthesized macroporous cross-linked copolymers of methyl acrylate-divinyl benzene (MA-DVB), acrylamide-N,N’-methylenebisacrylamide (AAM-BIS) and their functionalized products were used for immobilization ...<正> Synthesized macroporous cross-linked copolymers of methyl acrylate-divinyl benzene (MA-DVB), acrylamide-N,N’-methylenebisacrylamide (AAM-BIS) and their functionalized products were used for immobilization of aminoacylase from Aspergillus oryzae. Effects of the carrier properties on the activity of immobilized aminoacylase were investigated and effects of substrate concentration, pH, phosphate buffer concentration and temperature on the immobilized aminoacylase were compared with those of the soluble aminoacylase. A column of immobilized aminoaoylase was prepared and used for continuous resolution of N-acyl-DL-methionine; the operational stability of immobilized enzyme was also investigated.展开更多
基金Project supported by the National Natural Science Foundation of Chinathe 21st Century Foundation for Young Scholars of Tianjin
文摘<正> E.coli L-asparaginase,an antitumor enzyme,was chemically modified with N,O-carboxymethyl chitosan to lower its artigenicity and increase its plasma half-life.The results showed that the modified L-asparaginase has almost the same apparent Km value as that of native enzyme.The modified L-asparaginase also showed a higher protease stability against trypsin and a-chymotrypsin.After being modified,the enzyme exhibited the complete loss of antigenicity towards antiasparaginase serum.In addition,the higher the molecular weight of modifying reagents,the better the effects on reduction of antigenicity.When tested in vivo,the plasma half-life of the modified enzyme (t1/2=40 h) was over 33 times longer than that of the native enzyme (t1/2=1.2 h).
文摘<正> Synthesized macroporous cross-linked copolymers of methyl acrylate-divinyl benzene (MA-DVB), acrylamide-N,N’-methylenebisacrylamide (AAM-BIS) and their functionalized products were used for immobilization of aminoacylase from Aspergillus oryzae. Effects of the carrier properties on the activity of immobilized aminoacylase were investigated and effects of substrate concentration, pH, phosphate buffer concentration and temperature on the immobilized aminoacylase were compared with those of the soluble aminoacylase. A column of immobilized aminoaoylase was prepared and used for continuous resolution of N-acyl-DL-methionine; the operational stability of immobilized enzyme was also investigated.
