酪蛋白类蛋白物的溶剂分级和酶水解对ACE抑制活性的影响

Impact of solvent fractionation and enzymatic hydrolysis of casein hydrolysate modified by plastein reaction on its ACE inhibition

利用响应面法优化类蛋白反应条件修饰酪蛋白水解物制备酪蛋白类蛋白物。酪蛋白类蛋白物的ACE抑制活性高于酪蛋白水解物，IC50值从52．6mg／L降低到14．9mg／L。利用乙醇一水混合溶剂对酪蛋白水解物和类蛋白物进行分级，结果表明，极性最低的溶剂得到的上清液部分活性较高，而沉淀部分活性较低。4种蛋白酶水解酪蛋白类蛋白物的分级产物，导致活性下降，除碱性蛋白酶外，木瓜蛋白酶、胃蛋白酶和胰蛋白酶的水解产物AcE抑制活性为31．5%-46．8％，但是仍然高于酪蛋白水解物ACE抑制活性（27．8％），表明类蛋白反应提高了酪蛋白水解物对一些蛋白酶的体外抵抗能力。

The prepared hydrolysate was modified by the plastein reaction under the response-surface-methodology optimized conditions to prepare casein plasteins. The casein plasteins exhibited a higher ACE-inhibitory activity in vitro than the original hydrolysate as its value of IC50 was decreased from original 52.6 to 14.9 ug/mL. When the original hydrolysate or the plasteins was fractionated by ethanol-water sol- vents respective/y, the soluble fractions obtained by the solvent of the lowest polarity had a higher activity but the precipitate fractions a lower one. Further enzymatic hydrolysis of the fractionated products of the plasteins by four proteases would damage their activities. The analysis re- sults showed that the final hydrolyzed products of the plasteins by papain, pepsin or trypsin except for alcalase had a residue activity about 31.5%-46.8%, higher than the original hydrolysate （27.8%）. It was revealed that the carried out plastein reaction enhanced the resistance of ca- sein hydrolysate to some proteases in vitro.