Pagano M, Keppler D, Fumeron-Dalet V, Engler R
Biochem Cell Biol. 1986 Dec;64(12):1218-25. doi: 10.1139/o86-160.
The cathepsin B like proteinase present in ascitic fluid of a patient with neoplasia has been purified and characterized after pepsin activation. From this fluid we have prepared the low molecular weight (LMW) cysteine-proteinase inhibitors. Three major inhibitor forms were found with isoelectric points of 7.4, 5.4, and 5.1, respectively. The interaction of the enzyme with the former inhibitor was studied because this inhibitor was the most abundant. The Ki value was found to be 4.3 X 10(-8) M. Two molecules of this proteinase were bound by one molecule of plasma alpha 2 macroglobulin (alpha 2M). The LMW inhibitor was able to bind to the enzyme entrapped in alpha 2M and reduced its endopeptidase activity on benzyloxycarbonyl-L-phenylalanyl-L-arginine-4-methyl-7-coumarylamide. These results may have a physiological significance in the regulation of the enzyme which, among other extracellular hydrolases, probably plays an important role in tumor invasion.
对一名肿瘤患者腹水中存在的组织蛋白酶B样蛋白酶进行了胃蛋白酶激活后的纯化和特性鉴定。从该腹水中我们制备了低分子量（LMW）半胱氨酸蛋白酶抑制剂。发现了三种主要的抑制剂形式，其等电点分别为7.4、5.4和5.1。对该酶与前一种抑制剂的相互作用进行了研究，因为这种抑制剂含量最为丰富。发现Ki值为4.3×10⁻⁸M。该蛋白酶的两个分子与一个血浆α2巨球蛋白（α2M）分子结合。LMW抑制剂能够与包埋在α2M中的酶结合，并降低其对苄氧羰基-L-苯丙氨酰-L-精氨酸-4-甲基-7-香豆酰胺的内肽酶活性。这些结果在该酶的调节方面可能具有生理意义，该酶与其他细胞外水解酶一样，可能在肿瘤侵袭中起重要作用。
