Baskova I P, Nikonov G I
Biokhimiia. 1985 Mar;50(3):424-31.
The salivary gland secretion of the leech Hirudo medicinalis contains an enzyme termed by us as destabilase, which hydrolyzes the epsilon-(gamma-glutamyl)-lysine bonds as a result of fibrin stabilization by factor XIIIa in the presence of Ca2+. This hydrolysis, apart from the original lysine and glutamine, is characterized by an appearance of lysine and glutamic acid residues. The accumulation of glutamic acid residues leads to spontaneous depolymerization of the destabilized fibrin. As a result, fluid "spots" of destabilized fibrin depolymerization (DFD) begin to appear at the sites of leech secretion application on the surface of stabilized fibrin plates. The DFD activity of the leech salivary gland secretion manifests itself only in case of stabilized fibrin and increases with an increase in the stabilization degree. Treatment of leech secretion with diisopropylfluorophosphate does not affect the enzyme activity, which is completely blocked by monoiodoacetate. The mechanism of action of leech salivary gland secretion and the enzyme isolated from it, i. e., destabilase, was studied, using a synthetic chromogenic substrate - p-nitroanilide-gamma-glutamic acid. The amidolytic activity of leech salivary gland secretion is 2.2 +/- 0.18 nkat/ml, Km(app) for destabilase is 0.6 X 10(-5) M, V = 5.4 X 10(-3) mol/min.
医用水蛭唾液腺分泌物中含有一种我们称之为解稳酶的酶，在钙离子存在的情况下，该酶可水解由因子XIIIa稳定的纤维蛋白中的ε-（γ-谷氨酰）-赖氨酸键。这种水解作用除了产生原来的赖氨酸和谷氨酰胺外，还会出现赖氨酸和谷氨酸残基。谷氨酸残基的积累会导致解稳后的纤维蛋白自发解聚。结果，在稳定的纤维蛋白平板表面水蛭分泌物涂抹处开始出现解稳纤维蛋白解聚（DFD）的液体“斑点”。水蛭唾液腺分泌物的DFD活性仅在纤维蛋白稳定的情况下表现出来，并且随着稳定程度的增加而增强。用二异丙基氟磷酸处理水蛭分泌物不会影响酶活性，而单碘乙酸可完全抑制该酶活性。利用合成显色底物——对硝基苯胺-γ-谷氨酸，研究了水蛭唾液腺分泌物及其分离出的酶即解稳酶的作用机制。水蛭唾液腺分泌物的酰胺水解活性为2.2±0.18纳卡特/毫升，解稳酶的表观米氏常数为0.6×10⁻⁵摩尔，最大反应速度为5.4×10⁻³摩尔/分钟。
