Sujatha S, Jacob R T, Pattabiraman T N
Department of Biochemistry, Kasturba Medical College, Karnataka, India.
Biochem Med Metab Biol. 1988 Apr;39(2):217-25. doi: 10.1016/0885-4505(88)90079-5.
Incubation of human serum with cobra or viper venoms (10 micrograms/0.1 ml serum) caused negligible decrease in total protease inhibitory activity whereas alpha 2-macroglobulin activity was reduced by 67.0-82.0% in 16 hr. The action of venoms on MG activity was time dependent. Human alpha 2-macroglobulin activity was reduced to a much greater extent than goat or bovine factors by the venoms. While 25 micrograms venoms/0.1 ml serum caused 60-100% inhibition of human alpha 2-macroglobulin activity, the bovine factor was not affected under similar conditions. Goat alpha 2-macroglobulin was affected to the extent of 0-20%. Evidence is provided to show that venom proteases generate endogenous proteases in situ in human plasma or serum which in turn bind to alpha 2-macroglobulin. The venom-mediated action was abolished by prior dialysis of the serum or its dilution. Ethylenediaminetetraacetate at 10(-3) M concentration also blocked the reaction. While phenylmethylsulfonyl fluoride had no effect, pepstatin in the concentration range 10(-2) to 10(-3) M caused partial inhibition of the venom-mediated inhibition of alpha 2-macroglobulin activity in human serum.
将人血清与眼镜蛇或蝰蛇毒液（10微克/0.1毫升血清）一起孵育，总蛋白酶抑制活性仅有可忽略不计的下降，而α2-巨球蛋白活性在16小时内降低了67.0 - 82.0%。毒液对巨球蛋白（MG）活性的作用具有时间依赖性。毒液对人α2-巨球蛋白活性的降低程度远大于山羊或牛的相应因子。当25微克毒液/0.1毫升血清导致人α2-巨球蛋白活性受到60 - 100%的抑制时，在类似条件下牛的相应因子未受影响。山羊α2-巨球蛋白受影响程度为0 - 20%。有证据表明，毒液蛋白酶在人血浆或血清中原位产生内源性蛋白酶，这些内源性蛋白酶进而与α2-巨球蛋白结合。血清预先透析或稀释可消除毒液介导的作用。10⁻³ M浓度的乙二胺四乙酸也可阻断该反应。苯甲基磺酰氟无作用，浓度在10⁻²至10⁻³ M范围内的胃蛋白酶抑制剂对毒液介导的人血清中α2-巨球蛋白活性抑制有部分抑制作用。
