来自兔网织红细胞的线粒体结合型己糖激酶对Fe(II)/抗坏血酸诱导的失活具有抗性。

Mitochondria-bound hexokinase from rabbit reticulocytes is resistant to the inactivation induced by Fe(II)/ascorbate.

作者信息

Stocchi V, Fiorani M, Biagiarelli B, Piccoli G, Saltarelli R, Palma F, Cucchiarini L, Dachà M

机构信息

Istituto di Chimica Biologica Giorgio Fornaini, Università di Urbino, Italy.

出版信息

Biochem Mol Biol Int. 1995 Apr;35(5):1133-42.

PMID:7549932

Abstract

Exposure of rabbit reticulocytes to Fe(II)/ascorbate induced a pronounced decay in hexokinase activity. In reticulocytes, this enzyme is present in at least three different molecular forms, Ia, Ia* and Ib, sub-types of hexokinase type I, which show different intracellular distribution. Hexokinase Ia and Ib are soluble, whereas hexokinase Ia* is almost entirely bound to the mitochondria. Anion exchange chromatography of hexokinase from intact reticulocytes exposed to Fe(II)/ascorbate revealed a selective inactivation of forms Ia and Ib, whereas the form Ia* did not show any decay. Binding to the mitochondrial membrane seems to be responsible for the observed resistance of the form Ia* to the inactivation elicited by Fe(II)/ascorbate. Indeed, by using a cell-free system in which hexokinase Ia* was solubilized using Triton X-100, the decay in hexokinase activity induced by iron/ascorbate involved all three enzymatic forms.

摘要

将兔网织红细胞暴露于Fe(II)/抗坏血酸盐会导致己糖激酶活性显著下降。在网织红细胞中，这种酶至少以三种不同的分子形式存在，即己糖激酶I的亚型Ia、Ia和Ib，它们表现出不同的细胞内分布。己糖激酶Ia和Ib是可溶的，而己糖激酶Ia几乎完全与线粒体结合。对暴露于Fe(II)/抗坏血酸盐的完整网织红细胞中的己糖激酶进行阴离子交换色谱分析，发现Ia和Ib形式被选择性失活，而Ia形式没有表现出任何活性下降。与线粒体膜的结合似乎是观察到的Ia形式对Fe(II)/抗坏血酸盐引起的失活具有抗性的原因。事实上，通过使用一种无细胞系统，其中己糖激酶Ia*用 Triton X-100 溶解，铁/抗坏血酸盐诱导的己糖激酶活性下降涉及所有三种酶形式。