Mihara H, Sumi H, Yoneta T, Mizumoto H, Ikeda R, Seiki M, Maruyama M
Department of Physiology, Miyazaki Medical College, Japan.
Jpn J Physiol. 1991;41(3):461-72. doi: 10.2170/jjphysiol.41.461.
A strong fibrinolytic enzyme was readily obtained in saline extracts of the earthworm, Lumbricus rubellus. It hydrolyzed not only plasminogen-rich fibrin plates, but also plasminogen-free fibrin plates. The average fibrinolytic activity was about 100 CU (plasmin units) or 250 IU (urokinase units)/g wet weight. The molecular weight and isoelectric point were about 20,000 and 3.4, respectively. The enzyme was heat-stable and displayed a very broad optimal pH range. DFP and SBTI strongly inhibited the enzyme, but the anti-plasmin agent, t-AMCHA, exerted little effect under the same conditions. Purification of the enzyme was performed and three partially purified fractions were obtained. These three fractions were further subdivided. The first fraction (F-I) was divided into three fractions (F-I-0, F-I-1, and F-I-2), which exhibited similar biochemical characteristics. The second fraction (F-II) could not be subdivided. The third fraction (F-III) was divided into two fractions (F-III-1 and F-III-2). Based on results for their enzymatic activities against various substrates, the fraction I enzymes are thought to represent a chymotrypsin-like enzyme and the fraction III enzymes to represent a trypsin-like enzyme. The fraction II enzyme appears to be neither a trypsin- or chymotrypsin-like enzyme nor an elastase. The amino acid compositions of the six enzymes were estimated. Compared with other serine enzymes, these enzymes contained very abundant asparagine or aspartic acid, and there was very little proline or lysine. From the above data, these enzymes are regarded as novel fibrinolytic enzymes, and we name them collectively as Lumbrokinase from the generic name of the earthworm.
在赤子爱胜蚓的盐水提取物中很容易获得一种强力纤维蛋白溶解酶。它不仅能水解富含纤溶酶原的纤维蛋白平板，还能水解不含纤溶酶原的纤维蛋白平板。平均纤维蛋白溶解活性约为100 CU（纤溶酶单位）或250 IU（尿激酶单位）/克湿重。分子量和等电点分别约为20,000和3.4。该酶具有热稳定性，并且表现出非常宽的最佳pH范围。二异丙基氟磷酸（DFP）和大豆胰蛋白酶抑制剂（SBTI）强烈抑制该酶，但抗纤溶酶剂对甲苯磺酰-L-精氨酸甲酯（t-AMCHA）在相同条件下几乎没有影响。对该酶进行了纯化，获得了三个部分纯化的组分。这三个组分进一步细分。第一组分（F-I）分为三个组分（F-I-0、F-I-1和F-I-2），它们表现出相似的生化特性。第二组分（F-II）无法再细分。第三组分（F-III）分为两个组分（F-III-1和F-III-2）。根据它们对各种底物的酶活性结果，I组分的酶被认为代表一种胰凝乳蛋白酶样酶，III组分的酶被认为代表一种胰蛋白酶样酶。II组分的酶似乎既不是胰蛋白酶样或胰凝乳蛋白酶样酶，也不是弹性蛋白酶。估计了这六种酶的氨基酸组成。与其他丝氨酸酶相比，这些酶含有非常丰富的天冬酰胺或天冬氨酸，而脯氨酸或赖氨酸很少。根据上述数据，这些酶被视为新型纤维蛋白溶解酶，我们根据蚯蚓的属名将它们统称为蚓激酶。
