Bernlohr R W, Clark V
J Bacteriol. 1971 Jan;105(1):276-83. doi: 10.1128/jb.105.1.276-283.1971.
Extracts of growing and sporulating cells contain a protease activity that has a broad pH optimum and an unusually broad specificity. The activity, which resides in at least two protein fractions, hydrolyzes all peptide bonds and can reduce a mixture of proteins into a mixture of free amino acids with a high efficiency. No inhibitors of the activity were found, but the protease showed a definite preference for denatured protein as substrate. The synthesis of the intracellular protease activity is under catabolite repression control, as is the extracellular activity. However, the synthesis of the two activities is not coordinate, making the relationship between the two unclear. Due to (i) the specificity of the intracellular activity, (ii) the fact that it is synthesized most rapidly under slow or nongrowing conditions, and (iii) our inability to measure in vivo protein turnover in cells containing high levels of enzyme, a scavenger role is postulated for the enzyme. The rate of protein turnover is not a function of the protease content of the cells.
处于生长和孢子形成阶段的细胞提取物含有一种蛋白酶活性，其最适pH范围较宽，特异性也异常广泛。该活性至少存在于两个蛋白质组分中，能水解所有肽键，并可高效地将蛋白质混合物降解为游离氨基酸混合物。未发现该活性的抑制剂，但该蛋白酶对变性蛋白作为底物表现出明确的偏好。细胞内蛋白酶活性的合成受分解代谢物阻遏控制，细胞外活性也是如此。然而，这两种活性的合成并不协调，使得两者之间的关系尚不清楚。由于（i）细胞内活性的特异性，（ii）其在缓慢或非生长条件下合成最快这一事实，以及（iii）我们无法测量含有高水平该酶的细胞中的体内蛋白质周转率，因此推测该酶具有清除剂作用。蛋白质周转率不是细胞中蛋白酶含量的函数。
