Study of the structure of troponin-T by measuring the relative reactivities of lysines with acetic anhydride

Sarah E. Hitchcock, Charles J. Zimmerman, Christine Smalley

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39 Scopus citations

Abstract

The structure of troponin-T has been studied by measuring the relative reactivity of lysines with acetic anhydride using a competitive labeling method. Troponin-T was acetylated free and complexed with -I and -C in the native state with [3H]acetic anhydride, purified, and then combined with 14[C]troponin-T that had been acetylated in 6 m-guanidine · HCl. Peptides containing labeled lysines were isolated following chymotryptic and tryptic digestion and identified in the published sequence. The 3H 14C ratio of these peptides was used as a measure of relative accessibility of the lysines. Troponin-T contains 39 lysines; we have identified 35 of these in 22 different peptides. The region of troponin-T influenced by binding to the other troponin components is extensive and includes the C-terminal half of the molecule as well as some residues in the N-terminal half. The lysines showing the greatest change in reactivity are concentrated between residues 114 to 223. The reactivities of the troponin-T lysines labeled in native troponin were not significantly influenced by the binding of calcium to the calcium-specific binding sites of troponin-C. A model for the structure of troponin-T is proposed based on the present and previous studies.

Original languageEnglish (US)
Pages (from-to)125-151
Number of pages27
JournalJournal of molecular biology
Volume147
Issue number1
DOIs
StatePublished - Mar 25 1981
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Structural Biology
  • Molecular Biology

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