Dua R D, Gupta K
Arch Biochem Biophys. 1985 Feb 1;236(2):479-86. doi: 10.1016/0003-9861(85)90650-2.
Chemical modification of carboxypeptidase Ag1 from goat pancreas with phenylglyoxal or ninhydrin led to a loss of enzymatic activity. The inactivation by phenylglyoxal in 200 mM N-ethylmorpholine, 200 mM sodium chloride buffer, pH 8.0, or in 300 mM borate buffer, pH 8.0, followed pseudo-first-order kinetics at all concentrations of the modifier. The reaction order with respect to phenylglyoxal was 1.68 and 0.81 in 200 mM N-ethylmorpholine, 200 mM NaCl buffer and 300 mM borate buffer, pH 8.0, respectively, indicating modification of single arginine residue per mole of enzyme. The kinetic data were supported by amino acid analysis of modified enzyme, which also showed the modification of single arginine residue per mole of the enzyme. The modified enzyme had an absorption maximum at 250 nm, and quantification of the increase in absorbance showed modification of single arginine residue. Modification of arginine residue was protected by beta-phenylpropionic acid, thus suggesting involvement of an arginine residue at or near the active site of the enzyme.
用苯乙二醛或茚三酮对山羊胰腺羧肽酶Ag1进行化学修饰会导致酶活性丧失。在200 mM N - 乙基吗啡啉、200 mM氯化钠缓冲液（pH 8.0）或300 mM硼酸盐缓冲液（pH 8.0）中，苯乙二醛导致的失活在修饰剂的所有浓度下均遵循准一级动力学。在200 mM N - 乙基吗啡啉、200 mM NaCl缓冲液和300 mM硼酸盐缓冲液（pH 8.0）中，相对于苯乙二醛的反应级数分别为1.68和0.81，表明每摩尔酶有一个精氨酸残基被修饰。修饰酶的氨基酸分析支持了动力学数据，该分析也表明每摩尔酶有一个精氨酸残基被修饰。修饰酶在250 nm处有最大吸收峰，吸光度增加量的定量分析表明有一个精氨酸残基被修饰。精氨酸残基的修饰受到β - 苯丙酸的保护，因此表明该酶活性位点处或附近有一个精氨酸残基参与其中。
