Okamoto U, Nagamatsu Y, Amemiya T
Thromb Haemost. 1981 Apr 30;45(2):180-5.
An insoluble fibrinolytic enzyme with a molecular weight of approximately 30,000, was purified from the human spleen. A single protein band possessing fibrinolytic activity was obtained on polyacrylamide gel disk electrophoresis at pH 4.5. The enzyme, tentatively termed spleen fibrinolytic proteinase (SFP), degraded fibrinogen at neutral pH following Michaelis-Menten kinetics. The fibrinogenolytic activity was not inhibited by t-AMCHA, a specific plasmin inhibitor. SFP barely degraded certain synthetic ester or polypeptide substrates for trypsin, chymotrypsin, plasma, Xa, elastase and collagenase. These results indicate a different nature for SFP compared to other enzymes examined. SFP was found to digest no elastin and its fibrinogenolytic activity was strongly inhibited by STI, indicating that it was not an elastase. SFP required neither Zn++ nor CA++ for its fibrinogenolytic activity, indicating that it differed from metal-dependent proteinases such as collagenase. SFP was inhibited by DFP but not by TLCK, suggesting that it contains an active serine residue, but no trypsin type histidine at its active center. These results appear to show that SFP is a unique proteinase in the spleen, which is capable of degrading fibrin and fibrinogen at neutral pH.
从人脾脏中纯化出一种分子量约为30,000的不溶性纤维蛋白溶解酶。在pH 4.5的聚丙烯酰胺凝胶圆盘电泳上获得了一条具有纤维蛋白溶解活性的单一蛋白带。该酶暂称为脾脏纤维蛋白溶解蛋白酶（SFP），在中性pH下按照米氏动力学降解纤维蛋白原。特异性纤溶酶抑制剂t-AMCHA不抑制其纤维蛋白原分解活性。SFP几乎不降解某些用于胰蛋白酶、糜蛋白酶、血浆、Xa、弹性蛋白酶和胶原酶的合成酯或多肽底物。这些结果表明SFP与所检测的其他酶具有不同的性质。发现SFP不消化弹性蛋白，其纤维蛋白原分解活性受到大豆胰蛋白酶抑制剂（STI）的强烈抑制，表明它不是弹性蛋白酶。SFP的纤维蛋白原分解活性既不需要Zn++也不需要Ca++，这表明它不同于如胶原酶等金属依赖性蛋白酶。SFP受到二异丙基氟磷酸（DFP）的抑制，但不受甲苯磺酰-L-赖氨酸氯甲基酮（TLCK）的抑制，这表明它含有一个活性丝氨酸残基，但在其活性中心没有胰蛋白酶类型的组氨酸。这些结果似乎表明SFP是脾脏中一种独特的蛋白酶，能够在中性pH下降解纤维蛋白和纤维蛋白原。
