Howard J B, Swenson R, Eccleston E
Ann N Y Acad Sci. 1983;421:160-6. doi: 10.1111/j.1749-6632.1983.tb18106.x.
The inactivation of alpha 2M by the nucleophiles, NH4+, hydrazine, and methylamine, follows pseudo-first-order (second order, overall) rates. The rate of incorporation of nucleophiles however, is biphasic with the faster rate consistent with inactivation. Protease cleavage of alpha 2M is prevented by complete inactivation of alpha 2M by methylamine. Loss of protease cleavage is slower than methylamine incorporation but parallels inactivation. Our results are consistent with a complex model of sequential conformation changes leading to binding and inactivation of proteases by alpha 2M. Our results suggest that cross-linking of the protease to alpha 2M by aminolysis of the thiolester is not required for inactivation of the protease.
亲核试剂NH4+、肼和甲胺使α2M失活，遵循准一级（二级，总体）反应速率。然而，亲核试剂的掺入速率是双相的，较快的速率与失活一致。甲胺使α2M完全失活可防止α2M被蛋白酶切割。蛋白酶切割的丧失比甲胺掺入慢，但与失活平行。我们的结果与α2M导致蛋白酶结合和失活的连续构象变化的复杂模型一致。我们的结果表明，蛋白酶失活不需要通过硫酯的氨解使蛋白酶与α2M交联。
