{"title":"Isoenzyme der malatdehydrogenase und ihre regulation in Saccharomyces cerevisiae","authors":"Irene Witt, Rainer Kronau, Helmut Holzer","doi":"10.1016/0926-6593(66)90142-1","DOIUrl":null,"url":null,"abstract":"<div><p></p><ul><li><span>1.</span><span><p>1. From <em>Saccharomyces cerevisiae</em>, incubated on a glucose-free medium with acetate as the only carbon source, two different malate dehydrogenases (<span>l</span>-malate: NAD<sup>+</sup> oxidoreductase, EC 1.1.1.37) have been isolated by DEAE-cellulose ion-exchange chromatography. One of these enzymes was only found in the mitochondria and is called enzyme A or m-malate dehydrogenase; the other enzyme was found in the extramitochondrial c-space and is called enzyme B or c-malate dehydrogenase. At present it cannot be decided whether m-malate dehydrogenase also exists in the c-space or leaks when the mitochondria are injured.</p></span></li><li><span>2.</span><span><p>2. The reaction velocity plotted against the concentration of oxaloacetic acid showed a characteristic substrate inhibition in the case of m-malate dehydrogenase In contrast, c-malate dehydrogenase showed no substrate inhibition. This difference corresponds to the behaviour of m-malate dehydrogenase and c-malate dehydrogenase from liver.</p></span></li><li><span>3.</span><span><p>3. In yeast grown on glucose only m-malate dehydrogenase could be found, but after incubating the cells on acetate as the sole carbon source, both m-malate dehydrogenase and c-malate dehydrogenase were found. In reference to earlier experiments concerning the regulation of malate dehydrogenase activity in yeast, it is concluded that a repression of c-malate dehydrogenase synthesis by glucose occurs. This regulating mechanism is useful for the cell, because in the glycoxylate cycle c-malate dehydrogenase participates in the gluconeogenesis from acetate or ethanol. This enzyme is not necessary when glucose is in the medium.</p></span></li></ul></div>","PeriodicalId":100160,"journal":{"name":"Biochimica et Biophysica Acta (BBA) - Enzymology and Biological Oxidation","volume":null,"pages":null},"PeriodicalIF":0.0000,"publicationDate":"1966-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0926-6593(66)90142-1","citationCount":"84","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Biochimica et Biophysica Acta (BBA) - Enzymology and Biological Oxidation","FirstCategoryId":"1085","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/0926659366901421","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 84
Abstract
1.
1. From Saccharomyces cerevisiae, incubated on a glucose-free medium with acetate as the only carbon source, two different malate dehydrogenases (l-malate: NAD+ oxidoreductase, EC 1.1.1.37) have been isolated by DEAE-cellulose ion-exchange chromatography. One of these enzymes was only found in the mitochondria and is called enzyme A or m-malate dehydrogenase; the other enzyme was found in the extramitochondrial c-space and is called enzyme B or c-malate dehydrogenase. At present it cannot be decided whether m-malate dehydrogenase also exists in the c-space or leaks when the mitochondria are injured.
2.
2. The reaction velocity plotted against the concentration of oxaloacetic acid showed a characteristic substrate inhibition in the case of m-malate dehydrogenase In contrast, c-malate dehydrogenase showed no substrate inhibition. This difference corresponds to the behaviour of m-malate dehydrogenase and c-malate dehydrogenase from liver.
3.
3. In yeast grown on glucose only m-malate dehydrogenase could be found, but after incubating the cells on acetate as the sole carbon source, both m-malate dehydrogenase and c-malate dehydrogenase were found. In reference to earlier experiments concerning the regulation of malate dehydrogenase activity in yeast, it is concluded that a repression of c-malate dehydrogenase synthesis by glucose occurs. This regulating mechanism is useful for the cell, because in the glycoxylate cycle c-malate dehydrogenase participates in the gluconeogenesis from acetate or ethanol. This enzyme is not necessary when glucose is in the medium.