Structural and thermodynamic characterization of tropomyosin from fast skeletal muscle of bluefin tuna |
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Authors: | Ming-Chih HUANG Yoshihiro OCHIAI AND Shugo WATABE |
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Institution: | Laboratory of Aquatic Molecular Biology and Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo, Tokyo 113-8657, Japan |
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Abstract: | ABSTRACT: Tuna tropomyosin is a mixture of nearly equimolar amounts of two isoforms (designated α and β). cDNA encoding the α form was cloned from bluefin tuna Thunnus thynnus fast skeletal muscle. The full-length cDNA contained 1220 bp, comprising an open reading frame of 855 bp encoding 284 amino acid residues, flanked by 5'-untranslational regions (156 bp) and 3'-untranslational regions (209 bp). The deduced amino acid sequence showed considerably high homology in a range of 93.7–98.6% to those of other vertebrate α-type tropomyosins. In phylogenetic analysis, bluefin tuna tropomyosin showed the closest relationship with the white croaker counterpart. The predicted mass was 32 919 Da, and isoelectric point was 4.50, assuming acetylation of the N-terminus. By differential scanning calorimetry, bluefin tuna tropomyosin gave two major endothermic peaks at 29.3 and 41.5°C, probably caused by the presence of two isoforms. Circular dichroism spectra supported such a unique denaturation profile. |
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Keywords: | bluefin tuna cDNA cloning primary structure skeletal muscle thermostability tropomyosin |
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