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Adrenal Medullary Tropomyosins: Purification and Biochemical Characterization
Author(s) -
Côté A.,
Doucet J.P.,
Trifaró J.M.
Publication year - 1986
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1986.tb08495.x
Subject(s) - tropomyosin , molecular mass , biology , biochemistry , gel electrophoresis , adrenal medulla , polyacrylamide gel electrophoresis , isoelectric point , sodium dodecyl sulfate , microbiology and biotechnology , urea , isoelectric focusing , actin , chromatography , chemistry , endocrinology , enzyme , catecholamine
Tropomyosins have been isolated from bovine adrenal medulla. Purified from a heat‐stable extract, the adrenal medulfary tropomyosins show the same chromatographic patterns as platelet tropomyosin components purified under very similar conditions on ion‐exchange (DEAE‐Sephacel) and hydroxylapatite columns. When analyzed by polyacrylamide gel electrophoresis, the purified fraction, reduced and denatured, yielded three polypeptides with apparent molecular weights of 38,000, 35,500, and 32,000. The molar ratio of the two major polypeptides (38 kd and 32 kd) was 2:1. The predominant form of 38 kd is different from other nonmuscle tropomyosins previously isolated and with which an apparent molecular weight of 30,000 is normally associated. The three adrenal medullary tropomyosins have similar isoelectric points of about 4.7. When adrenal tropomyosins were subjected to sodium dodecyl sulfate‐polyacrylamide gel electrophoresis in the presence of 8 M urea, each form showed a shift to a higher molecular weight, which is a characteristic of muscle tropomyosin. The 38,000 adrenal medullary tropomyosin exhibits a stronger affinity for F‐actin than the other forms. Peptide profiles obtained after limited proteolytic digestion show some similarity between the two predominant tropomyosins of the bovine adrenal medulla and also between these and the α and β forms of bovine skeletal muscle tropomyosin.