title: Thermostability of striated and smooth adductor muscle tropomyosins from Yesso scallop Mizuhopecten yessoensis.
abstract: The striated and smooth adductor muscle tropomyosins (TMs) of Yesso scallop Mizuhopecten yessoensis have been known to express different isoforms, but have not been characterized in detail to date. In the present study, TMs from both muscles of Yesso scallop were purified and their stabilities were compared by circular dichroism (CD) spectrometry and differential scanning calorimetry (DSC). From the CD data, the apparent melting temperature and the apparent free energy of folding at 20 degrees C were calculated to be 30.5 degrees C and -13.4 kJ/mol, and 36.0 degrees C and -31.9 kJ/mol for the striated and smooth muscle TMs, respectively. From the DSC data, DeltaH values were calculated to be 1.87 x 10(3) and 2.19 x 10(3) kJ/mol for striated and smooth muscle TMs. These results suggest that smooth muscle TM has higher thermostability than striated muscle TM. The amino acid residues responsible for such stability difference were considered to be the six amino acid substitutions in the middle region of the TM molecules.
authors.affiliation: Laboratory of Aquatic Molecular Biology and Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo, Tokyo 113-8657, Japan.
authors.forename: Hideo
authors.initials: H
authors.lastname: Ozawa
authors.forename: Shugo
authors.initials: S
authors.lastname: Watabe
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Ochiai
mesh_terms: D000818:Animals; D002152:Calorimetry, Differential Scanning; D002942:Circular Dichroism; D009130:Muscle, Smooth / Q000737:chemistry*; D009132:Muscles / Q000737:chemistry*; D049897:Pectinidae; D011489:Protein Denaturation; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics; D017433:Protein Structure, Secondary; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013696:Temperature; D013816:Thermodynamics; D014335:Tropomyosin / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification
chemical_list: D020033:Protein Isoforms; D014335:Tropomyosin