Sakurai M, Watanabe B, Nagata S, Ichikawa M
Department of Hospital Pharmacy, Nagasaki University School of Medicine, Japan.
Biol Chem. 1997 Feb;378(2):77-81. doi: 10.1515/bchm.1997.378.2.77.
The partial amino acid sequence of subfragment-1 of adult chicken atrial myosin was determined by direct protein sequencing. Subfragment-1 was prepared by limited digestion of adult chicken atrial myosin with alpha-chymotrypsin. Ten peptides were then obtained by cleaving this subfragment with cyanogen bromide. The amino acid composition and amino acid sequence of the obtained peptides were subsequently determined. By sequence comparison with the corresponding region of adult chicken ventricular myosin, three peptides, with differing sequences that corresponded to the same position in subfragment-1, were detected. This indicates that at least three isoforms of atrial myosin exist in adult chicken atrial muscle. One of the three peptides was identical to ventricular subfragment-1 while the remaining two peptides were markedly different. Furthermore, four of these ten peptides were completely different from ventricular subfragment-1. These four peptides were presumed to be fragments of atrial-specific myosin heavy chain protein. Results suggest the expression of at least two species of atrial-specific myosin heavy chain in the atrial muscle of adult chickens.
通过直接蛋白质测序确定了成年鸡心房肌球蛋白亚片段-1的部分氨基酸序列。亚片段-1是通过用α-胰凝乳蛋白酶对成年鸡心房肌球蛋白进行有限消化制备的。然后用溴化氰切割该亚片段获得了十个肽段。随后测定了所得肽段的氨基酸组成和氨基酸序列。通过与成年鸡心室肌球蛋白的相应区域进行序列比较，检测到三个在亚片段-1中对应相同位置但序列不同的肽段。这表明成年鸡心房肌中至少存在三种心房肌球蛋白同工型。这三个肽段中的一个与心室亚片段-1相同，而其余两个肽段明显不同。此外，这十个肽段中的四个与心室亚片段-1完全不同。这四个肽段被推测为心房特异性肌球蛋白重链蛋白的片段。结果表明成年鸡心房肌中至少表达两种心房特异性肌球蛋白重链。
