Al3+ versus Ca2+ ion binding to methionine and tyrosine spin-labeled bovine brain calmodulin

Guofeng You, Donald J. Nelson

Research output: Contribution to journalArticle

20 Scopus citations

Abstract

Bovine calmodulin analogues, spin-labeled at either methionine or tyrosine residues, have been utilized in electron paramagnetic resonance (EPR) studies to investigate possible calmodulin interactions with aluminum ion. The study attempts to clarify a previous report in the literature (H. Siegel, R. Coughlin, and A. Haug, Biochem. Biophys. Res. Commun. 115, 512 (1983)) which indicated, on the basis of EPR experiments on methionine spin-labeled protein, significant interaction between calmodulin and aluminum ion at pH = 6.5. In EPR metal ion titration experiments we have found that the signal line-shape (from both methionine and tyrosine spin labels) changed dramatically with the addition of calcium ion, but was virtually unchanged with the addition of aluminum ion at pH = 6.5. Experiments performed at pH = 5.5, where significantly more "free" aluminum ion (i.e., Al(H2O)63+ = Al3+) is present, also failed to produce the line-narrowing effect observed in the earlier study. Based on our EPR experiments, in the pH range 5.5 to 6.5, we find no evidence for significant interaction between calmodulin and aluminum ion.

Original languageEnglish (US)
Pages (from-to)283-291
Number of pages9
JournalJournal of Inorganic Biochemistry
Volume41
Issue number4
DOIs
StatePublished - Jan 1 1991
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Inorganic Chemistry

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