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Studies on the interaction of the dye, Stains‐all, with individual calcium‐binding domains of calmodulin
Author(s) -
Sharma Yogendra,
Gopalakrishna Aradhyam,
Balasubramanian Dorairajan,
Fairwell Thomas,
Krishna Gopal
Publication year - 1993
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(93)81761-n
Subject(s) - calmodulin , calcium , binding site , chemistry , calcium binding protein , biophysics , circular dichroism , biochemistry , stereochemistry , biology , organic chemistry
We show that the calcium‐mimic dye, Stains‐all, is a convenient probe to study the structural features of the individual calcium‐binding sites of calmodulin (CaM) and related calcium‐binding proteins (CaBP). These peptides bind the dye in their calcium‐binding sites, and induce a circular dichroism (CD) band in the bound dye in the 620 nm (J band) region, which is abolished upon the addition of calcium. Replacement of Asp by Asn in the + x position of the weaker calcium‐binding site (site I of CaM) abolishes the dye binding, while the same change in the higher affinity site IV attenuates the binding of the dye and does not abolish it. Replacement of Tyr in site IV with Trp does not distort the geometry, although it increases the dye binding affinity.