Huang Ming-Chih, Ochiai Yoshihiro
Laboratory of Aquatic Molecular Biology and Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo, Tokyo 113-8657, Japan.
Comp Biochem Physiol B Biochem Mol Biol. 2005 Aug;141(4):461-71. doi: 10.1016/j.cbpc.2005.05.008.
Tropomyosin (TM) was isolated from the fast skeletal muscle of six fish species, whose amino acid sequences of this protein have already been revealed. The thermal stability of these TMs was measured by differential scanning calorimetry (DSC) and circular dichroism (CD), while the molecular weights were measured by mass spectrometry. The results showed clear differences in thermostability among these fish TMs, though the identity of amino acid sequences was more than 93.3%. Therefore, only a few amino acid substitutions could affect the overall stability of the TM molecule. Especially, several residues located on the molecular surface were considered to be responsible for such stability difference. In contrast, the molecular weights of these TMs as measured by mass spectrometry were higher than those calculated from amino acid composition, suggesting the presence of post-translational modification(s) which could also affect their thermal stability.
原肌球蛋白（TM）是从六种鱼类的快肌中分离出来的，其该蛋白质的氨基酸序列已被揭示。通过差示扫描量热法（DSC）和圆二色性（CD）测量这些TM的热稳定性，同时通过质谱法测量分子量。结果表明，尽管这些鱼类TM的氨基酸序列同一性超过93.3%，但它们在热稳定性上存在明显差异。因此，只有少数氨基酸取代可能会影响TM分子的整体稳定性。特别是，位于分子表面的几个残基被认为是造成这种稳定性差异的原因。相比之下，通过质谱法测得的这些TM的分子量高于根据氨基酸组成计算出的分子量，这表明存在翻译后修饰，其也可能影响它们的热稳定性。
