香蕉中的磷酸葡萄糖异构酶：部分特性及与成熟过程中碳水化合物组成主要变化的关系

Phosphoglucose isomerase from bananas: partial characterization and relation to main changes in carbohydrate composition during ripening.

作者信息

Cordenunsi B R, Oliveira do Nascimento J R, Vieira da Mota R, Lajolo F M

机构信息

Department of Food Science and Experimental Nutrition, College of Pharmaceutical Sciences, University of São Paulo, SP, Brasil.

出版信息

Biosci Biotechnol Biochem. 2001 Oct;65(10):2174-80. doi: 10.1271/bbb.65.2174.

DOI:10.1271/bbb.65.2174

PMID:11758906

Abstract

Some characteristics of phosphoglucose isomerase (PGI, EC 5.3.1.9) from banana were measured during fruit ripening of three banana cultivars. In banana, PGI was present as two dimeric isoenzymes, named PGI1 and PGI2, which had similar native molecular masses but differed in relation to heat stability and isoelectric point. Total PGI activity showed a distinct two-step change during fruit ripening. Before the climacteric period, PGI activity gradually decreased with the starch content, then its activity began to increase with sucrose accumulation. The ratio of PGI1, and PGI2 was constant, indicating that both enzymes would be involved in starch degradation and sucrose synthesis. PGI activity and changes in carbohydrate composition suggests the existence of some control to fit the requirements of the intense carbon flow from starch to sucrose.

摘要

在三个香蕉品种果实成熟过程中，对香蕉磷酸葡萄糖异构酶（PGI，EC 5.3.1.9）的一些特性进行了测定。在香蕉中，PGI以两种二聚体同工酶形式存在，命名为PGI1和PGI2，它们具有相似的天然分子量，但在热稳定性和等电点方面存在差异。总PGI活性在果实成熟过程中呈现出明显的两步变化。在呼吸跃变期之前，PGI活性随淀粉含量逐渐降低，然后随着蔗糖积累其活性开始增加。PGI1和PGI2的比例恒定，表明这两种酶都参与淀粉降解和蔗糖合成。PGI活性和碳水化合物组成的变化表明存在某种调控机制，以满足从淀粉到蔗糖的强烈碳流需求。