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Studies on Paratropomyosin which Contributes to Meat Tenderization

有助于肉类嫩化的副肌球蛋白的研究

基本信息

批准号：
61470140
负责人：
TAKAHASHI Koui
金额：
$ 3.84万
依托单位：
Hokkaido University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1986
资助国家：
日本
起止时间：
1986 至 1988
项目状态：
已结题

项目摘要

1. Paratropomyosin inhibited the Mg-ATPase activity and enhanced K-ATPase activity of myofibrils stoichiometrically, and its maximal binding to actin was estimated to occur at a molar ratio of 1:13. These results indicate that paratropomyosin is able to bind to thin filaments of myofibrils, and that due to its greater affinity for the myosin binding site on actin, paratropomyosin competes for the binding site and helps weaken rigor linkages formed between actin and myosin.2. Intact myofibrils stained with fluorescent antibodies against paratropomyosin showed that paratropomyosin was exclusively located at the A-I junction of sarcomeres. In stretched myofibrils (3.7 mum in sarcomere length), the approximate width of the fluorescent stripes and their relation to the A band remained constant. During postmortem storage of muscles, on the other hand, paratropomyosin was translocated from its original position at the A-I junction onto thin filaments. The translocation of paratropomyosin was … More successfully induced with a calcium ion concentration of 0.1 mM in the presence of protease inhibitors.3. The rigor tension of glycerinated fibers was reduced to about 65% of the initial value within 10 min after the addition of purified paratropomyosin, whereas it remained constant for at least 3.5 hr in control fibers. Paratropomyosin showed a stronger effect on the increase in sarcomere length of passively stretched fibers, which developed weaker tensions. The most successful rigor solution contained 0.2-0.25 M KC1, pH 5.5, at 5-10゜C. Under these conditions, which coincide well those of postmortem muscles, the sarcomere length was easily increased from 2.4 to 3.6 mum, if rigor-contracted fibers were passively stretched after the addition of purified paratropomyosin. We therefore conclude that in postrigor muscles, paratropomyosin is released from the A-I junction region following the increase in the sarcoplasmic calcium ion concentration to 0.1 mM, and then binds to thin filaments, which results in weakening of rigor linkages formed between actin and myosin. Less

1. 从化学计量学的角度来看，副atropomyosin抑制了肌原纤维mg - atp酶的活性，增强了k - atp酶的活性，估计其与肌动蛋白的最大结合发生在1:13的摩尔比下。这些结果表明，副atropomyosin能够结合到肌原纤维的细丝上，由于它对肌动蛋白上的肌球蛋白结合位点具有更大的亲和力，因此它会竞争结合位点，并有助于削弱肌动蛋白和肌球蛋白之间形成的紧密联系。用抗副atropomyosin荧光抗体染色的完整肌原纤维显示，副atropomyosin仅位于肉瘤的A-I连接处。在拉伸后的肌原纤维（肌节长度为3.7 mm）中，荧光条纹的大致宽度及其与A带的关系保持不变。另一方面，在死后的肌肉储存过程中，para - atropomyosin从其在A-I连接处的原始位置转移到细丝上。在蛋白酶抑制剂存在的情况下，钙离子浓度为0.1 mM更能诱导副atropomyosin易位。在加入纯化的副atropomyosin后的10分钟内，甘油纤维的张力降低到初始值的65%左右，而在对照纤维中，张力保持不变至少3.5小时。副atropomyosin对被动拉伸纤维的肌节长度的增加有更强的影响，从而产生较弱的张力。最成功的溶液含有0.2-0.25 M KC1, pH 5.5，温度为5-10 C。在这些条件下，与死后肌肉的情况完全一致，如果在添加纯化的副atropomyosin后被动拉伸严格收缩的纤维，肌节长度很容易从2.4增加到3.6。因此，我们得出结论，在肌萎缩后肌肉中，当肌浆钙离子浓度增加到0.1 mM时，从A-I连接区释放出副atropomyosin，然后结合到细丝上，这导致肌动蛋白和肌凝蛋白之间形成的紧密联系减弱。少