Bruns W, Dermietzel R, Gros G
J Physiol. 1986 Feb;371:351-64. doi: 10.1113/jphysiol.1986.sp015980.
Sarcoplasmic reticulum vesicles and mitochondria were prepared from red and white skeletal muscles of the rabbit. The preparations were characterized in terms of their specific activities of citrate synthase, basal (Mg2+-dependent) and Ca2+-dependent ATPase (the latter two in the presence of NaN3 and ouabain), and their specific carbonic anhydrase activities were determined. Skeletal muscle mitochondria had high specific activities of citrate synthase (700-1200 mu. mg protein-1) and low carbonic anhydrase activities (0.1-0.4 u. ml mg protein-1). The latter are likely to be due to a contamination of the preparations with sarcoplasmic reticulum (s.r.) Preparations of s.r. vesicles showed negligible activities of citrate synthase and the expected differing patterns of basal and Ca2+-dependent ATPase in red and white muscles. Specific carbonic anhydrase activities in s.r. from both muscle types were high (2-4 u. ml mg protein-1). The highest carbonic anhydrase activity, 11 u. ml mg protein-1, was found in s.r. from rabbit m. masseter. The inhibition constant of s.r. carbonic anhydrase towards acetazolamide was 4-6 X 10(-8) M and similar but not identical to that of cytosolic carbonic anhydrase II. It appears possible that the carbonic anhydrase II-like enzyme previously found by us in muscle homogenates (Siffert & Gros, 1982) originates from the s.r. Histochemical studies using the dansylsuphonamide method described previously (Dermietzel, Leibstein, Siffert, Zamboglou & Gros, 1985) showed an intracellular pattern of carbonic anhydrase staining compatible with the presence of the enzyme in s.r.: spots homogeneously distributed across the fibre cross-sections in transversely sectioned fibres and thin, longitudinally oriented, bands in longitudinally sectioned fibres. It is estimated that s.r. carbonic anhydrase accelerates CO2 hydration within the s.r. approximately 1000-fold. Thus, CO2 and HCO3- react fast enough to provide a rapid source and sink for protons leaving and entering the s.r. in exchange for Ca2+.
从兔的红色和白色骨骼肌中制备肌浆网囊泡和线粒体。通过柠檬酸合酶的比活性、基础（Mg2+依赖性）和Ca2+依赖性ATP酶（后两者在NaN3和哇巴因存在的情况下）对这些制剂进行表征，并测定其特异性碳酸酐酶活性。骨骼肌线粒体具有高的柠檬酸合酶比活性（700 - 1200 μ·mg蛋白-1）和低的碳酸酐酶活性（0.1 - 0.4 u·ml mg蛋白-1）。后者可能是由于制剂被肌浆网（s.r.）污染所致。肌浆网囊泡制剂显示柠檬酸合酶活性可忽略不计，并且在红色和白色肌肉中基础和Ca2+依赖性ATP酶呈现预期的不同模式。两种肌肉类型的肌浆网中的特异性碳酸酐酶活性都很高（2 - 4 u·ml mg蛋白-1）。在兔咬肌的肌浆网中发现了最高的碳酸酐酶活性，为11 u·ml mg蛋白-1。肌浆网碳酸酐酶对乙酰唑胺的抑制常数为4 - 6×10(-8) M，与胞质碳酸酐酶II相似但不完全相同。我们之前在肌肉匀浆中发现的类似碳酸酐酶II的酶（Siffert & Gros，1982）似乎可能源自肌浆网。使用先前描述的丹磺酰胺法（Dermietzel、Leibstein、Siffert、Zamboglou & Gros，1985）进行的组织化学研究显示，碳酸酐酶染色的细胞内模式与该酶在肌浆网中的存在情况相符：在横切纤维的纤维横截面上均匀分布的斑点，以及在纵切纤维中纵向排列的细带。据估计，肌浆网碳酸酐酶可使肌浆网内的CO2水合加速约1000倍。因此，CO2和HCO3-反应足够快，能够为与Ca2+交换进出肌浆网的质子提供快速的来源和汇。
