兔骨骼肌组织蛋白酶B对肌原纤维蛋白及肌原纤维结构的作用机制

Mode of action of rabbit skeletal muscle cathepsin B towards myofibrillar proteins and the myofibrillar structure.

Matsuishi M, Matsumoto T, Okitani A, Kato H

Department of Food Science and Technology, Nippon Veterinary and Animal Science University, Tokyo, Japan.

Int J Biochem. 1992 Dec;24(12):1967-78. doi: 10.1016/0020-711x(92)90293-a.

Abstract

The mode of degradation of myofibrillar proteins and the structural changes in myofibrils due to the action of cathepsin B highly purified from rabbit skeletal muscle were studied. 2. Cathepsin B degraded myosin heavy chain, actin and troponin T, but not alpha-actinin, tropomyosin, troponin I or troponin C among myofibrillar proteins. 3. Cathepsin B optimally degraded myosin heavy chain, actin and troponin T at around pH 5. Degradation of myosin heavy chain produced 6 fragments, 180,000, 150,000, 87,000, 81,000, 75,000 and 69,000 Da, respectively. Actin was hydrolyzed into fragments of 41,000, 38,000 and 30,000 Da. Troponin T was degraded into fragments of 21,000, 12,000 and 10,000 Da. 4. Cathepsin B caused the fragmentation of myofibrils and disturbance of the lateral arrangement of myofibrils. 5. Cathepsin B partly disintegrated the Z-line and the M-line, and induced disordering of the arrangement of filaments in the I-band.

摘要

研究了兔骨骼肌中高度纯化的组织蛋白酶B的作用导致的肌原纤维蛋白降解模式以及肌原纤维的结构变化。2. 组织蛋白酶B可降解肌球蛋白重链、肌动蛋白和肌钙蛋白T，但在肌原纤维蛋白中不降解α-辅肌动蛋白、原肌球蛋白、肌钙蛋白I或肌钙蛋白C。3. 组织蛋白酶B在pH 5左右时能最佳地降解肌球蛋白重链、肌动蛋白和肌钙蛋白T。肌球蛋白重链的降解产生了6个片段，分子量分别为180,000、150,000、87,000、81,000、75,000和69,000 Da。肌动蛋白被水解成分子量为41,000、38,000和30,000 Da的片段。肌钙蛋白T被降解成分子量为21,000、12,000和10,000 Da的片段。4. 组织蛋白酶B导致肌原纤维断裂并扰乱肌原纤维的横向排列。5. 组织蛋白酶B使Z线和M线部分解体，并导致I带中细丝排列紊乱。