Molecular and Biological Studies on Cardiac Muscle Calcium-Binding Protein (TN-C)

1 January 1975

journal article
Published by Canadian Science Publishing in Canadian Journal of Biochemistry

Vol. 53 (1) , 15-20
https://doi.org/10.1139/o75-003

Abstract

TN-C was purified from bovine cardiac muscle. In the absence of Ca²⁺, cardiac TN-C has an intrinsic sedimentation coefficient of 1.93 S and a molecular weight of 18 000 daltons. Cardiac TN-C reverses the inhibitory effect of skeletal TN-I on the Mg²⁺-activated ATPase of a skeletal synthetic actomyosin preparation in the presence of skeletal tropomyosin. Circular dichroism (CD) studies indicate that cardiac TN-C undergoes a major conformational Change upon binding Ca²⁺. A similar response is elicited by Sr²⁺, whereas Mg²⁺ has a much less pronounced effect. The presence of Mg²⁺ does not alter the net effects of either Ca²⁺ or Sr²⁺. Cardiac TN-C is rich in acidic amino acid residues. UV absorption, near UV CD, and fluorimetric studies show that the protein lacks tryptophan and has a relatively high phenylalanine to tyrosine ratio. The results of this study invite direct comparisons with results reported for the skeletal muscle analogue of cardiac TN-C.

Keywords

This publication has 0 references indexed in Scilit: