Church F C, Griffith M J
Biochem Biophys Res Commun. 1984 Nov 14;124(3):745-51. doi: 10.1016/0006-291x(84)91021-0.
Covalent modification with pyridoxal 5'-phosphate was used to study the function of lysyl residues in heparin cofactor II, a heparin-dependent plasma protease inhibitor. Reduction of the Schiff base with sodium borohydride resulted in modification of 3-4 lysyl residues of heparin cofactor II at high concentrations of pyridoxal 5'-phosphate, one of which was protected in the presence of heparin. The antithrombin activity of modified heparin cofactor II was enhanced compared to the native protein. However, the heparin cofactor activity for thrombin inhibition was reduced significantly or completely eliminated in the modified protease inhibitor depending on the extent of phosphopyridoxylation. In contrast to native heparin cofactor II, the modified protease inhibitor did not bind to a heparin-agarose column. The results suggest that lysyl residues are essential for heparin cofactor activity during thrombin inhibition.
用磷酸吡哆醛进行共价修饰，以研究肝素辅因子II（一种依赖肝素的血浆蛋白酶抑制剂）中赖氨酰残基的功能。在高浓度的磷酸吡哆醛存在下，用硼氢化钠还原席夫碱导致肝素辅因子II的3 - 4个赖氨酰残基被修饰，其中一个在肝素存在下受到保护。与天然蛋白相比，修饰后的肝素辅因子II的抗凝血酶活性增强。然而，根据磷酸吡哆醛化的程度，在修饰后的蛋白酶抑制剂中，其抑制凝血酶的肝素辅因子活性显著降低或完全消除。与天然肝素辅因子II不同，修饰后的蛋白酶抑制剂不与肝素 - 琼脂糖柱结合。结果表明，赖氨酰残基在抑制凝血酶过程中对肝素辅因子活性至关重要。
