Whipple G, Koohmaraie M, Arbona J R
US Department of Agriculture(†), ARS, Roman L. Hruska US Meat Animal Research Center, PO Box 166, Clay Center, NE 68933, USA.
Meat Sci. 1994;38(1):133-9. doi: 10.1016/0309-1740(94)90102-3.
The objective of this study was to determine the effect of 30 mM CaCl(2) on the solubilization of those structural proteins that contribute to myofibril stability. Ovine M. longissimus dorsi (longissimus) samples were obtained immediately post-exsanguination, myofibrils were isolated, glycerated, and frozen until needed. Myofibrils were washed, diluted and incubated in 0·1 m KCl, 10 mm Tris, pH 7·0 buffer for 24, 48 and 72 h. Treatments consisted of: (1) control, (2) 1 mm E(64), (3) 30 mm CaCl(2), and (4) 1 mm E(64) + 30 mm CaCl(2). Results (SDS-PAGE) indicated that myosin heavy chain (though not to a great extent), M-protein, C-protein, α-actinin, actin, troponin-T, tropomyosin isoforms, troponin-I and 72, 70, 62, 33, 32, 30, and 22 kDa unidentified bands were solubilized from myofibrils incubated in KCl buffer for 72 h. The addition of CaCl(2) hastened the appearance of some of the proteins in the supernatant fractions, but no differences were observed at 72 h among the treatments. The addition of E(64) had no effect on which proteins were released. Thus, in the absence of proteolysis it appears that a general solubilization of thick-and-thin filament ancillary proteins occurs in the presence of 30 mm CaCl(2). However, the contribution to tenderness should be minimal, because solubilized proteins are not part of the cytoskeletal elements that are responsible for maintaining structural integrity of the tissue.
本研究的目的是确定30 mM氯化钙对那些有助于肌原纤维稳定性的结构蛋白溶解的影响。在放血后立即获取绵羊背最长肌（背最长肌）样本，分离、甘油化肌原纤维，并冷冻保存直至需要时使用。将肌原纤维洗涤、稀释，然后在0·1 m氯化钾、10 mm Tris、pH 7·0缓冲液中孵育24、48和72小时。处理组包括：（1）对照组，（2）1 mm E(64)，（3）30 mm氯化钙，以及（4）1 mm E(64) + 30 mm氯化钙。结果（SDS-PAGE）表明，在氯化钾缓冲液中孵育72小时的肌原纤维中，肌球蛋白重链（尽管程度不大）、M蛋白、C蛋白、α-辅肌动蛋白、肌动蛋白、肌钙蛋白-T、原肌球蛋白同工型、肌钙蛋白-I以及72、70、62、33、32、30和22 kDa的未鉴定条带被溶解。添加氯化钙加速了上清液部分中一些蛋白质的出现，但在72小时时各处理组之间未观察到差异。添加E(64)对释放哪些蛋白质没有影响。因此，在没有蛋白水解的情况下，似乎在30 mm氯化钙存在时，粗细肌丝辅助蛋白会普遍溶解。然而，对嫩度的贡献应该很小，因为溶解的蛋白质不是负责维持组织结构完整性的细胞骨架成分的一部分。
