桑叶总黄酮对蛋白质硝基化的抑制作用及其机理

研究了桑叶总黄酮对蛋白质硝化反应的抑制作用及其抑制机理.以牛血清白蛋白(BSA)为硝化底物、ONOO-为硝化试剂,pH 7.2的PBS缓冲溶液为反应体系,根据428nm处吸光度的变化来反映硝基蛋白含量的变化.实验研究发现,在37℃,pH 7.2,反应时间90min以及BSA与ONOO-终浓度比为1∶6,桑叶总黄酮的浓度为3.640×10-3 g.L-1时,对硝化反应的抑制作用最强,抑制率可达55.70%.推测其抑制机理可能是桑叶总黄酮与ONOO-直接作用或清除ONOO-均裂产生的.OH和.NO2,进而抑制硝化反应的进行,而不是还原硝基化产物.桑叶总黄酮对硝化反应较强的抑制作用,为开发桑叶总黄酮为蛋白质硝化反应的抑制剂提供了理论依据.

Inhibiting Effect of Mulberry Total Flavonoid on Protein Nitration and Its Mechanism

This article probed into the inhibiting effect of mulberry total flavonoid on protein nitration and its mechanism.Bovine serum albumin(BSA) was selected as nitrated substrate and peroxynitrite as nitrification reagent.The changes of absorption strength at 428 nm can be assigned to reflect the concentration of nitro-protein.When the concentrations of mulberry total flavonoid was 3.640×10-3 g·L-1,the inhibtion rate reached 55.70% under the conditions of pH 7.2,temperature 37 ℃,90 min for reaction time and the final concentration ratio of BSA and ONOO-was 1∶6.It is possible that mulberry total flavonoid directly reacted with ONOO-or scavenged ·OH and ·NO2 generated by ONOO-,and then blocked the nitration reaction rather than restore the nitration product.Mulberry total flavonoid has strong inhibitory effect on nitrification,and hence provides a theoretical basis for the development of nitrification inhibitors for protein.