钙离子对来自不同肌肉的海藻糖酶、己糖激酶、磷酸果糖激酶、果糖二磷酸酶和丙酮酸激酶活性的影响。

The effects of calcium ions on the activities of trehalase, hexokinase, phosphofructokinase, fructose diphosphatase and pyruvate kinase from various muscles.

作者信息

Vaughan H, Thornton S D, Newsholme E A

出版信息

Biochem J. 1973 Mar;132(3):527-35. doi: 10.1042/bj1320527.

DOI:10.1042/bj1320527

PMID:4353381

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC1177617/

Abstract

The effects of Ca(2+) on the activities and regulatory properties of trehalase, hexokinase, phosphofructokinase, fructose diphosphatase and pyruvate kinase from vertebrate red and white muscle and insect fibrillar and non-fibrillar muscle have been investigated. These muscles were selected because of the possible difference in the role of glycolysis in energy production in the vertebrate muscles, and the possible difference in the role of Ca(2+) in the control of contraction in the two types of insect muscle. An increase in Ca(2+) concentration from 0.001mum to 10mum did not modify the activities nor did it modify the regulatory properties of these enzymes from these various muscles. 2. Concentrations of Ca(2+) above 0.1mm inhibited the activities of hexokinase and phosphofructokinase from the different muscles. It has been suggested that this inhibition may provide the basis for a theory of regulation of glycolysis (Margreth et al., 1967). If phosphofructokinase is located within the sarcoplasmic reticulum, its activity will be inhibited when the muscle is at rest, but the release of Ca(2+) from the reticulum during contraction will lead to a stimulation of its activity and hence an increase in glycolytic flux. The distribution of hexokinase and phosphofructokinase in the various cell fractions of these muscles was very variable. In particular, both enzymes were present almost exclusively in the 100000g supernatant fraction in the extracts of insect flight muscles. Thus there is no correlation between the properties of the enzymes and their distribution in muscle. 3. It is concluded that Ca(2+) does not control the activities of the important regulatory enzymes of glycolysis in muscle. It is suggested that in some muscles the sensitivity of the control mechanism at the level of phosphofructokinase to changes in the concentration of AMP may be increased by a process known as ;substrate-cycling'.

摘要

研究了钙离子对脊椎动物红肌和白肌以及昆虫纤维状肌和非纤维状肌中海藻糖酶、己糖激酶、磷酸果糖激酶、果糖二磷酸酶和丙酮酸激酶活性及调节特性的影响。选择这些肌肉是因为糖酵解在脊椎动物肌肉能量产生中的作用可能存在差异，以及钙离子在两种昆虫肌肉收缩控制中的作用可能存在差异。钙离子浓度从0.001微摩尔升至10微摩尔既未改变这些酶的活性，也未改变其调节特性。2. 高于0.1毫摩尔的钙离子浓度抑制了不同肌肉中己糖激酶和磷酸果糖激酶的活性。有人认为这种抑制作用可能为糖酵解调节理论提供基础（Margreth等人，1967年）。如果磷酸果糖激酶位于肌浆网内，那么在肌肉静止时其活性会受到抑制，但收缩过程中肌浆网释放钙离子会导致其活性增强，从而使糖酵解通量增加。这些肌肉不同细胞组分中己糖激酶和磷酸果糖激酶的分布差异很大。特别是，这两种酶几乎只存在于昆虫飞行肌提取物的100000克上清液组分中。因此，酶的特性与其在肌肉中的分布之间没有相关性。3. 得出的结论是，钙离子并不控制肌肉中糖酵解重要调节酶的活性。有人认为，在某些肌肉中，通过一种称为“底物循环”的过程，磷酸果糖激酶水平的控制机制对AMP浓度变化的敏感性可能会增加。