Mason R W, Massey S D
Department of Biochemistry, Virginia Polytechnic Institute and State University, Blacksburg 24061.
Biochem Biophys Res Commun. 1992 Dec 30;189(3):1659-66. doi: 10.1016/0006-291x(92)90268-p.
Pro-cathepsin L is an inactive zymogen that has been shown previously to undergo autolysis at pH 3.0 to give mature forms of the enzyme. We have now been able to demonstrate that this enzyme can undergo activation at pH 5.5 in the presence of negatively charged surfaces. Activation could also be measured at pH 6.0, but no activation occurred at pH 6.5 or higher. The initiation of activation depends upon the presence of a small percentage of active pro-enzyme, and this is then followed by a more rapid activation to give mature forms of the enzyme. No significant intermediate molecular forms of the enzyme were seen. The time taken for processing of the pro-enzyme to single-chain mature enzyme is comparable to that seen in biosynthetic pulse-chase experiments.
组织蛋白酶L前体是一种无活性的酶原，先前已证明它在pH 3.0时会发生自溶，从而产生该酶的成熟形式。我们现在已经能够证明，在带负电荷的表面存在的情况下，这种酶可以在pH 5.5时被激活。在pH 6.0时也可以检测到激活，但在pH 6.5或更高时没有激活发生。激活的起始取决于一小部分活性酶原的存在，随后是更快的激活，以产生该酶的成熟形式。未观察到该酶有明显的中间分子形式。将酶原加工成单链成熟酶所需的时间与生物合成脉冲追踪实验中观察到的时间相当。
