Katoh T, Katoh H, Morita F
Department of Chemistry, Faculty of Science, Hokkaido University.
J Biochem. 1988 Apr;103(4):633-5. doi: 10.1093/oxfordjournals.jbchem.a122319.
The binding of one of the alkali light chains of myosin, A1, with the isolated renatured 20-kDa fragment of myosin subfragment-1 heavy chain was demonstrated by means of difference UV absorption spectroscopy. The difference spectrum with either rabbit or chicken A1 showed two characteristic peaks at 279 and 287 nm indicating a perturbation of tyrosyl chromophores by the association with the 20-kDa fragment. The delta epsilon at 287 nm increased with an increase in the molar ratio of A1/20-kDa fragment and reached a maximum value at around equimolar ratio. The maximum delta epsilon value was approximately three times larger with rabbit A1 than with chicken A1. Based on the positions of Tyr residues in the amino acid sequences, the contact surface of A1 with myosin heavy chain was concluded to be spread over a large area of A1. The binding of 20-kDa fragment with F-actin was measured by following the increase in turbidity. The affinity appeared to increase several times in the presence of A1. A1 may possibly control the affinity of myosin for actin.
通过差示紫外吸收光谱法证明了肌球蛋白的一种碱性轻链A1与分离复性的肌球蛋白亚片段-1重链的20 kDa片段之间的结合。兔或鸡A1的差示光谱在279和287 nm处显示出两个特征峰，表明与20 kDa片段结合后酪氨酸发色团受到扰动。287 nm处的Δε随A1/20 kDa片段摩尔比的增加而增加，并在等摩尔比左右达到最大值。兔A1的最大Δε值约为鸡A1的三倍。根据氨基酸序列中酪氨酸残基的位置，得出A1与肌球蛋白重链的接触表面分布在A1的大面积上。通过跟踪浊度的增加来测量20 kDa片段与F-肌动蛋白的结合。在A1存在下，亲和力似乎增加了几倍。A1可能控制肌球蛋白对肌动蛋白的亲和力。
