分子量对酪蛋白多肽抗氧化活性的影响

在对酪蛋白酶解产物制备工艺进行优化的基础上,对不同分子量抗氧化肽(>3ku,1～3ku,<1ku)的抗氧化活性进行了评价。首先对酶的种类、酶底物比及水解时间进行了单因素实验,最终确定采用碱性蛋白酶,在pH8.0,55℃,底物浓度5%,酶底物比0.192AU/g的条件下,酶解4h所得水解物抗氧化活性最高。经过超滤和凝胶过滤层析分离获得不同分子量的抗氧化肽,并采用2,2′-连氮基-双-(3-乙基苯并二氢噻唑啉-6-磺酸)二铵盐(ABTS+.)、羟自由基和超氧自由基清除活性评价其抗氧化性。结果表明,ABTS+.清除活性与分子量呈负相关(r=-0.898,p<0.01),分子量低于1ku组分活性最强(2mg/mL,Trolox当量为2.08±0.05mmol/L);分子量低于3ku的抗氧化肽羟自由基清除活性较高(IC50:1～3ku,4.43±0.03mg/mL;<1ku,4.35±0.06mg/mL);分子量高于3ku组分主要分布在3～5ku,超氧自由基清除活最强(10mg/mL,66.1%±1.0%)。

Effect of molecular weight on the antioxidant activity of casein peptide

Optimization of enzymatic process was studied to prepare antioxidant peptides from casein and the effect of molecular weight on antioxidant activities of peptides was evaluated.Casein was hydrolyzed by three proteases(Alcalase,Papain and Trypsin)respectively and the optimum enzymatic hydrolysis parameters were determined by single-factor test.With substrate concentration of 5%,the hydrolysate hydrolyzed by Alcalase for 4h at pH 8.0 and 55℃ exhibited the highest antioxidant activity and the ratio of enzyme to substrate was 0.192AU/g.Antioxidant activities of peptide fractions with different molecular weights(>3ku,1～3ku,<1ku)which were separated by ultrafiltration and gel filtration chromatography were investigated.Results showed that 2,2’-azinobis(3-ethylbenzothiazoline-6-sulphonic acid)diammonium salt(ABTS+·)scavenging activity was negatively correlated to molecular weight of the antioxidant peptides(r=-0.898,p<0.01),and the fraction of <1ku exhibited the highest activity(2mg/mL,Trolox equivalent:2.08±0.05mmol/L).The fractions of <3ku exhibited stronger hydroxyl radical scavenging activity(IC50:1～3ku,4.43±0.03mg/mL;<1ku,4.35±0.06mg/mL).The fraction of >3ku mainly composed of peptides distributed in 3～5ku exhibited the highest superoxide radical scavenging activity(10mg/mL,66.1%±1.0%).