Calcium-induced conformational changes and mutual interactions of troponin components as studied by spin labeling.

Calcium-induced conformational changes and mutual interactions of troponin components as studied by spin labeling. Research Abstract Details 

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Calcium-induced conformational changes and mutual interactions of troponin components as studied by spin labeling. Abstract Text:

S Onishi,K Maruyama,S Ebashi,

The three troponin components, TN-C, TN-I, and TN-T, were spin-labeled with two different derivatives of the nitroxide radical, a maleimide and an imidazole reagent. The ESR spectra of various combinations of labeled and unlabeled components were measured both in the presence and absence of calcium. Conformational changes due to the binding of the components and also due to the binding of calcium were sensitively detected in many combinations as large changes in the spectrum. The conformation of TN-C was modified by both TN-T and TN-I. The effects were larger in the presence of calcium than in its absence. In the presence of calcium, TN-T and TN-I both showed large effects with the maleimide label, while TN-I showed a larger effect than TN-T with the imidazole label. In the absence of calcium, the effect of TN-I was larger than that of TN-T. The senstivitiy of TN-C to calcium was magnified by component binding, since the conformation of TN-C itself was not greatly affected by calcium. The conformation of TN-I was greatly altered only in the presence of both TN-C and calcium. This indicates that the calcium-induced conformational change in TN-C is transmitted to the adjacent TN-I. In reconstituted troponin, the conformation of TN-C was more influenced by TN-I in the presence of calcium and by TN-T in its absence as indicated by the imidazole label. With the maleimide label, TN-I was more influential in the absence of calcium. The effect of calcium on the troponin complex was to make the local environment of the label more rigid. The half-maximal effect was observed at 2 X 10(-6)M calcium with TN-I in various complexes, while it was 10(-5)M with TN-C in the complexes. In any case the calcium effects became discernible at 10(-6)M and saturated at 10(-4)M.

Calcium-induced conformational changes and mutual interactions of troponin components as studied by spin labeling. Publishing Authors By Initials

S Onishi,K Maruyama,S Ebashi,

For similar macromolecular substances: polymers: biopolymers: microfilament proteins: troponin research abstracts see: macromolecular substances: polymers: biopolymers: microfilament proteins: troponin research

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Calcium-induced conformational changes and mutual interactions of troponin components as studied by spin labeling. Journal Published:

PUBLICATION TYPE: Journal Article

Journal: Journal of biochemistry

VOLUME: 78

Page Numbers: 73-81

Journal Abbreviation: J. Biochem.

ISSN: 0021-924X

DAY: 19

MONTH: Jul

YEAR: 1975

Calcium-induced conformational changes and mutual interactions of troponin components as studied by spin labeling. Information

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LANGUAGE: eng

NlmUniqueID: 376600

Calcium-induced conformational changes and mutual interactions of troponin components as studied by spin labeling. Keywords Mesh Terms:

KEYWORDS: Troponin

MESH TERMS: metabolism

Chemical & Substance for Abstract: Calcium-induced conformational changes and mutual interactions of troponin components as studied by spin labeling. Information

Substance Name: Calcium

Registry Number: 7440-70-2

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Country: JAPAN

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MEDLINETA: J Biochem

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