Machovich R, Litwiller R D, Owen W G
Section of Hematology Research, Mayo Clinic and Foundation, Rochester, Minnesota 55905.
Biochemistry. 1992 Nov 24;31(46):11558-61. doi: 10.1021/bi00161a038.
In physiological salt solutions, porcine plasminogen is refractory to activation by urokinase or trypsin and to proteolysis at Lys77 by plasmin or trypsin. Plasminogen becomes a substrate for urokinase (at Arg560), plasmin (at Lys77), and trypsin (at both bonds) if chloride ion is removed or if 6-aminohexanoate (2.5 mmol/L) is added. Irrespective of salts, activation of des(1-77)plasminogen is as efficient as activation of des(kringle1-4)plasminogen and is inhibited 50% by 2.5 mmol/L 6-aminohexanoate. In solutions lacking chloride or containing 6-aminohexanoate, plasminogen, des(1-77)plasminogen, and des(kringle1-4)plasminogen show no tendency to saturate urokinase in physiologically relevant concentrations (10 mumol/L). The findings are interpreted as indicating that plasminogen requires modification, either by proteolysis or by ligands, for activation.
在生理盐溶液中，猪纤溶酶原对尿激酶或胰蛋白酶的激活以及纤溶酶或胰蛋白酶在赖氨酸77处的蛋白水解具有抗性。如果去除氯离子或添加6-氨基己酸（2.5 mmol/L），纤溶酶原就会成为尿激酶（在精氨酸560处）、纤溶酶（在赖氨酸77处）和胰蛋白酶（在两个位点）的底物。无论盐类情况如何，去（1-77）纤溶酶原的激活与去（kringle1-4）纤溶酶原的激活效率相同，并且会被2.5 mmol/L的6-氨基己酸抑制50%。在缺乏氯离子或含有6-氨基己酸的溶液中，纤溶酶原、去（1-77）纤溶酶原和去（kringle1-4）纤溶酶原在生理相关浓度（10 μmol/L）下均无饱和尿激酶的趋势。这些发现被解释为表明纤溶酶原需要通过蛋白水解或配体进行修饰才能被激活。
