Hough R, Pratt G, Rechsteiner M
J Biol Chem. 1987 Jun 15;262(17):8303-13.
We have purified two high molecular weight proteases approximately 400-fold from rabbit reticulocyte lysate. Both enzymes hydrolyze 125I-alpha-casein and 4-methylcoumaryl-7-amide peptides with tyrosine, phenylalanine, or arginine at the P1 position. Both are inhibited by hemin, thiol reagents, chymostatin, and leupeptin. They differ, however, by other criteria. Degradation of 125I-lysozyme-ubiquitin conjugates and succinyl-Leu-Leu-Val-Tyr-4-methylcoumaryl-7-amide by the larger 26 S protease is stimulated by ATP. Based on sedimentation, gel filtration, and nondenaturing polyacrylamide gel electrophoresis, the ATP-dependent protease has a molecular weight of 1,000,000 +/- 100,000 and is a multisubunit complex. The smaller 20 S protease has a molecular weight of 700,000 +/- 20,000 and is composed of 8-10 separate subunits with Mr values between 21,000 and 32,000. It does not require nucleotides for degradation of protein or peptide substrates. This smaller enzyme is similar, if not identical, to the "multicatalytic proteinase complex" first described by Wilk and Orlowski (Wilk, S., and Orlowski, M. (1983) J. Neurochem. 40, 842-849).
我们已从兔网织红细胞裂解物中纯化出两种高分子量蛋白酶，纯化倍数约为400倍。这两种酶均能水解125I-α-酪蛋白以及在P1位置含有酪氨酸、苯丙氨酸或精氨酸的4-甲基香豆素-7-酰胺肽。二者均受血红素、硫醇试剂、抑肽酶和亮抑酶肽抑制。然而，根据其他标准，它们存在差异。较大的26S蛋白酶对125I-溶菌酶-泛素缀合物和琥珀酰-Leu-Leu-Val-Tyr-4-甲基香豆素-7-酰胺的降解受ATP刺激。基于沉降、凝胶过滤和非变性聚丙烯酰胺凝胶电泳，依赖ATP的蛋白酶分子量为1,000,000±100,000，是一种多亚基复合物。较小的20S蛋白酶分子量为700,000±20,000，由8 - 10个独立亚基组成，亚基的Mr值在21,000至32,000之间。它在降解蛋白质或肽底物时不需要核苷酸。这种较小的酶即便不完全相同，也与Wilk和Orlowski首次描述的“多催化蛋白酶复合物”相似（Wilk, S., and Orlowski, M. (1983) J. Neurochem. 40, 842 - 849）。
