黄鳝内脏碱性磷酸酶功能基团的初步研究

经Tris—HCl缓冲液（pH8．6）抽提，正丁醇脱脂，硫酸绥分级沉淀分离，DEAE—Sepharose Fast Flow和Sephacryl S-200柱层析，从黄鳝内脏中提取出电泳纯的碱性磷酸酶。用PCMB，NBS，PMSF，TNBS，SUAN，DTT及IAA在一定条件下选择性修饰该酶的各种氨基酸残基，并对酶活力的变化作出测定。结果表明，PMSF，NBS，TNBS，SUAN和DTT的修饰能显著抑制酶的活性，且酶活力降低程度与修饰别的浓度相关；IAA和PCMB的修饰不表现对酶的抑制作用。初步认为，Ser，Lys和Trp残基为黄鳝碱性磷酸酶的必需功能基团，部分二硫键对保护酶的催化能力是必需的。

STUDIES OF THE FUNCTIONAL GROUPS OF ALKALINE PHOSPHATASE IN THE VISCERA OF MONPTENRUS ALBUS

The amino acid residues of the alkaline phosphatase(AKP) from Monptenrus albus were selectively modified by PMSF,DTT,PCMB,NBS,TNBS,SUAN and IAc,and the changes in their activity were monitored.It was found that the reaction of AKP with PMSF,NBS,TNBS,SUAN and DTT resulted in a strong inhibition of the enzyme activity,which decreased with the increase in modifier concentration.Modification by IAA and PCMB showed no inhibition to enzyme activity.It is thus tentatively assumed that Ser,Lys and Trp residues are essential functional groups of AKP while partial disulfide bond is essential for the catalytic capacity of the protective enzyme.