Laboratory of Aquatic Molecular Biology and Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo, Tokyo 113-8657, Japan.
J Biochem. 2010 Jun;147(6):823-32. doi: 10.1093/jb/mvq018. Epub 2010 Feb 17.
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.
有研究表明，虾夷扇贝（Mizuhopecten yessoensis）横纹肌和平滑肌的肌球蛋白结合蛋白 TMs 表达不同的同工型，但尚未进行详细的特征描述。本研究中，从虾夷扇贝的两种肌肉中纯化了 TMs，并通过圆二色性（CD）光谱法和差示扫描量热法（DSC）比较了它们的稳定性。从 CD 数据可以计算出，横纹肌和平滑肌 TMs 的表观熔点和 20°C 时的折叠表观自由能分别为 30.5°C 和-13.4 kJ/mol，以及 36.0°C 和-31.9 kJ/mol。从 DSC 数据可以计算出，横纹肌和平滑肌 TMs 的ΔH 值分别为 1.87×10(3)和 2.19×10(3)kJ/mol。这些结果表明，平滑肌 TM 比横纹肌 TM 具有更高的热稳定性。造成这种稳定性差异的氨基酸残基被认为是 TM 分子中部的六个氨基酸取代。
