Z. Grabarek , W. Drabikowski , L. Vinokurov , R.C. Lu
{"title":"Digestion of troponin C with trypsin in the presence and absence of Ca2+. Identification of cleavage points","authors":"Z. Grabarek , W. Drabikowski , L. Vinokurov , R.C. Lu","doi":"10.1016/0005-2795(81)90138-0","DOIUrl":null,"url":null,"abstract":"<div><p>The rate of tryptic digestion of troponin C has been shown to be dependent on Ca<sup>2+</sup> (Drabikowski et al., Biochim. Biophys. Acta 490, 216–224). We have characterized the tryptic peptides produced both in the presence and absence of Ca<sup>2+</sup> using amino acid composition and end-group analyses. In the presence of Ca<sup>2+</sup> trypsin cleaves TnC at Arg-8, Lys-84 and Lys-88, leading to the formation of two large peptides, one containing the two low-affinity sites (TR<sub>1</sub>C), the other, the two high-affinity Ca<sup>2+</sup>-binding sites (TR<sub>2</sub>C). In the absence of Ca<sup>2+</sup> (1 mM EDTA), digestion proceeds much more rapidly and takes place first at Arg-100, followed by Arg-104, Arg-120, Lys-153, Arg-8 and others. The data suggest that the points of cleavage are determined by the Ca<sup>2+</sup>-dependent conformational states of TnC, particularly in the C-terminal half of the protein where the cation is known to induce secondary structure.</p></div>","PeriodicalId":100165,"journal":{"name":"Biochimica et Biophysica Acta (BBA) - Protein Structure","volume":"671 2","pages":"Pages 227-233"},"PeriodicalIF":0.0000,"publicationDate":"1981-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0005-2795(81)90138-0","citationCount":"16","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Biochimica et Biophysica Acta (BBA) - Protein Structure","FirstCategoryId":"1085","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/0005279581901380","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 16
Abstract
The rate of tryptic digestion of troponin C has been shown to be dependent on Ca2+ (Drabikowski et al., Biochim. Biophys. Acta 490, 216–224). We have characterized the tryptic peptides produced both in the presence and absence of Ca2+ using amino acid composition and end-group analyses. In the presence of Ca2+ trypsin cleaves TnC at Arg-8, Lys-84 and Lys-88, leading to the formation of two large peptides, one containing the two low-affinity sites (TR1C), the other, the two high-affinity Ca2+-binding sites (TR2C). In the absence of Ca2+ (1 mM EDTA), digestion proceeds much more rapidly and takes place first at Arg-100, followed by Arg-104, Arg-120, Lys-153, Arg-8 and others. The data suggest that the points of cleavage are determined by the Ca2+-dependent conformational states of TnC, particularly in the C-terminal half of the protein where the cation is known to induce secondary structure.