微生物产生的淀粉酶抑制剂研究Ⅲ淀粉酶抑制剂抑制动力学研究

STUDIES ON THE INIBITION KINETICS OF AMYLASE INHIBITOR

Ｓ－２－３５淀粉酶抑制剂是一种易溶于水、不溶于有机溶剂的白色粉末，其紫外谱图呈末端吸收，红外谱图在３３９１、１５７２、１４１０、１０３０及９２７ｃｍ￣（－１）处有明显吸收峰。该抑制剂在ｐＨ６．５的条件下对ａ－淀粉酶有明显的抑制作用（ＩＤ＿（５０）为１．７×１０－５ｍｏｌ／Ｌ）．在３７℃，ｐＨ６．５的磷酸缓冲液中，Ｓ－２－３５抑制剂对淀粉酶的抑制作用与抑制剂的浓度关系密切，在抑制剂浓度较小的情况下，抑制剂与酶的结合呈直线关系，随着抑制剂浓度增大，残留活力曲线则出现漂移。根据Ｄｉｘｏｎ图和Ｌｉｎｅｗｅａｖｅｒ－Ｂｕｒｋ图的研究表明，Ｓ－２－３５淀粉酶抑制剂对淀粉酶的结合和底物呈竞争性抑制，抑制常数Ｋ＿ｉ为１．５～１．６×１０￣（－６）ｍｏｌ／Ｌ。

S-2-35 amylase inhibitor is a white powder,soluble inwater and insoluble for organsic agents.It presents the end absorption inUV spectrum and shows IR absorption peaks in 3391,1572,1410,1030and 927cm-1.The inhibition of the inhibitor to the a-amylase is strongID50=1.7 × 10-5mol/L when pH=6.5 and the inhibitory activity is closely related to the concentration of the inhibitor,In the case of the small in-hibitor concentration,there will be a linear relationship for the combi-ation of the inhibitor and amylase,Based on the stadies of Dixon plots and Lineweaver-Burk plots,the S-2-35 amylase inhibitor demonstrates competitive inhibition for amylase,The inhi bitory constant(Ki) is l.5～1.6× 10-6mol/L.