透析大鼠乳腺精氨酸酶中锰重构及巯基暴露的动力学

Kinetics of manganese reconstitution and thiol group exposition in dialyzed rat mammary gland arginase.

Fuentes J M, Campo M L, Soler G

Departamento de Bioquímica, Facultad de Veterinaria, Universidad de Extremadura, Cáceres, Spain.

Int J Biochem. 1994 May;26(5):653-9. doi: 10.1016/0020-711x(94)90165-1.

Abstract

Rat mammary gland arginase is a metallo-enzyme dependent on Mn2+, which can be only partially substituted by Cd2+. 2. Reconstitution of the activity of dialyzed arginase by manganese is a two-phase process; the second phase is independent of the cation concentration, with a half-time recovery (t1/2) of 10.77 min. 3. The apparent Km for Mn2+ is 280 microM and 10.5 microM for enzyme dialyzed for 24 and 72 hr, respectively. 4. Treatment with 5 mM EDTA at pH 6 totally inhibits enzyme activity, which is reconstituted by Mn2+. 5. Results obtained with iodoacetamide treatment suggest the existence of sulphydryl groups accessible only when the enzyme is dialyzed.

摘要

大鼠乳腺精氨酸酶是一种依赖于Mn2 +的金属酶，Cd2 +只能部分替代Mn2 +。2. 用锰重建透析精氨酸酶的活性是一个两相过程；第二阶段与阳离子浓度无关，半衰期恢复时间（t1/2）为10.77分钟。3. 对于分别透析24小时和72小时的酶，Mn2 +的表观Km分别为280 microM和10.5 microM。4. 在pH 6下用5 mM EDTA处理可完全抑制酶活性，该活性可由Mn2 +重建。5. 碘乙酰胺处理的结果表明，仅在酶透析时才存在可及的巯基。