{"title":"Aspartate transcarbamylase from Escherichia coli I. Inhibition by inorganic anions","authors":"Kjell Kleppe","doi":"10.1016/0926-6593(66)90037-3","DOIUrl":null,"url":null,"abstract":"<div><p></p><ul><li><span>1.</span><span><p>1. The effect of different inorganic anions on the catalytic activity of native and subunit aspartate transcarbamylase (carbamoylphosphate: <span>l</span>-aspartate carbamoltransferase, EC 2.1.3.2) has been investigated at pH 7.0 and 25°.</p></span></li><li><span>2.</span><span><p>2. Several inorganic anions were found to inhibit both native and subunit aspartate transcarbamylase. The order of effectiveness for the best inhibitors was: <span><math><mtext>PP</mtext><msub><mi></mi><mn>i</mn></msub><mtext> > F</mtext><msup><mi></mi><mn>−</mn></msup><mtext> > P</mtext><msub><mi></mi><mn>i</mn></msub><mtext> > SO</mtext><msub><mi></mi><mn>4</mn></msub><msup><mi></mi><mn>2−</mn></msup></math></span>.</p></span></li><li><span>3.</span><span><p>3. For each ion except F<sup>−</sup>, a strict competitive relationship was observed between the anion inhibitors and the substrate carbamyl phosphate.</p></span></li><li><span>4.</span><span><p>4. The concentration of <span>l</span>-aspartate also greatly influenced the magnitude of the inhibition. The inhibition increased with increasing concentration of <span>l</span>-aspartate.</p></span></li><li><span>5.</span><span><p>5. The effect of F<sup>−</sup> was shown to be due to a displacement of the pH curve along the pH axis. F<sup>−</sup> inhibited native asparatate transcarbamylase below pH 8 and activated it above this pH.</p></span></li><li><span>6.</span><span><p>6. Possible mechanisms of inhibition are discussed, and it is suggested that an inhibitor-<span>l</span>-aspartate complex is formed at the active site.</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":"1966-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0926-6593(66)90037-3","citationCount":"29","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/0926659366900373","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 29
Abstract
1.
1. The effect of different inorganic anions on the catalytic activity of native and subunit aspartate transcarbamylase (carbamoylphosphate: l-aspartate carbamoltransferase, EC 2.1.3.2) has been investigated at pH 7.0 and 25°.
2.
2. Several inorganic anions were found to inhibit both native and subunit aspartate transcarbamylase. The order of effectiveness for the best inhibitors was: .
3.
3. For each ion except F−, a strict competitive relationship was observed between the anion inhibitors and the substrate carbamyl phosphate.
4.
4. The concentration of l-aspartate also greatly influenced the magnitude of the inhibition. The inhibition increased with increasing concentration of l-aspartate.
5.
5. The effect of F− was shown to be due to a displacement of the pH curve along the pH axis. F− inhibited native asparatate transcarbamylase below pH 8 and activated it above this pH.
6.
6. Possible mechanisms of inhibition are discussed, and it is suggested that an inhibitor-l-aspartate complex is formed at the active site.