The inhibitory effects of methyl cinnamate on the monophenolase activity and diphenolase activity of tyrosinase were studied by enzymological kinetic method in Na2HPO4-NaH2PO4 buffer solution(pH=6.8) at 30 ℃.Methyl c...The inhibitory effects of methyl cinnamate on the monophenolase activity and diphenolase activity of tyrosinase were studied by enzymological kinetic method in Na2HPO4-NaH2PO4 buffer solution(pH=6.8) at 30 ℃.Methyl cinnamate was found to inhibit the monophenolase activity and diphenolase activity of tyrosinase.The methyl cinnamate concentration leading to 50 % inhibitory rate(IC50) were 0.61 mmol/L for monophenolase activity and 1.49 mmol/L for diphenolase activity,respectively.Methyl cinnamate coued extend the lag time of monophenolase.0.8 mmol/L of methyl cinnamate resulted in the lag time extension from 1.1 min to 3.2 min.The inhibition kinetics analyzed by Lineweaver-Burk plots indicated that methyl cinnamate was a noncompetitive inhibitor to diphenolase,and the inhibition constant KI for inhibitor binding with enzyme(E)was 0.66 mmol/L.展开更多
将罗非鱼的酶解产物及其超滤组分（〈5 k D酶解肽）加入罗非鱼鱼糜制品中,研究其在冷藏（0~4℃）期间对油脂和蛋白质的抗氧化效果。结果表明：酶解产物及超滤组分均可以改善鱼糜的色泽（P〈0.05）,尤其是超滤组分的效果接近于一定剂量的...将罗非鱼的酶解产物及其超滤组分（〈5 k D酶解肽）加入罗非鱼鱼糜制品中,研究其在冷藏（0~4℃）期间对油脂和蛋白质的抗氧化效果。结果表明：酶解产物及超滤组分均可以改善鱼糜的色泽（P〈0.05）,尤其是超滤组分的效果接近于一定剂量的VC;酶解产物对鱼糜中的油脂、蛋白质均表现出较强的抗氧化能力（P〈0.05）,其中超滤组分优于酶解液;酶解肽可以有效地保持鱼糜在冷藏期间的品质,超滤分离富集的〈5 k D的小分子肽显示出更好的抗氧化效果。展开更多
文摘采用酶动力学方法研究了香草酸对酪氨酸酶单酚酶和二酚酶活力的抑制效应。结果表明,香草酸对酪氨酸酶单酚酶和二酚酶活性均有抑制作用,导致单酚酶活力和二酚酶活力下降50%的香草酸浓度(IC50)约分别为1.3 mmol/L和2.6 mmol/L。香草酸能明显延长单酚酶的迟滞时间,2 mmol/L香草酸能使迟滞时间由1.1 m in延长至4.7 m in。香草酸对二酚酶的抑制作用表现为混合型抑制,对游离酶的抑制常数(KI)和对酶-底物络合物的抑制常数(KIS)分别为1.76 mmol/L和8.57 mmol/L。
文摘The inhibitory effects of methyl cinnamate on the monophenolase activity and diphenolase activity of tyrosinase were studied by enzymological kinetic method in Na2HPO4-NaH2PO4 buffer solution(pH=6.8) at 30 ℃.Methyl cinnamate was found to inhibit the monophenolase activity and diphenolase activity of tyrosinase.The methyl cinnamate concentration leading to 50 % inhibitory rate(IC50) were 0.61 mmol/L for monophenolase activity and 1.49 mmol/L for diphenolase activity,respectively.Methyl cinnamate coued extend the lag time of monophenolase.0.8 mmol/L of methyl cinnamate resulted in the lag time extension from 1.1 min to 3.2 min.The inhibition kinetics analyzed by Lineweaver-Burk plots indicated that methyl cinnamate was a noncompetitive inhibitor to diphenolase,and the inhibition constant KI for inhibitor binding with enzyme(E)was 0.66 mmol/L.
文摘将罗非鱼的酶解产物及其超滤组分（〈5 k D酶解肽）加入罗非鱼鱼糜制品中,研究其在冷藏（0~4℃）期间对油脂和蛋白质的抗氧化效果。结果表明：酶解产物及超滤组分均可以改善鱼糜的色泽（P〈0.05）,尤其是超滤组分的效果接近于一定剂量的VC;酶解产物对鱼糜中的油脂、蛋白质均表现出较强的抗氧化能力（P〈0.05）,其中超滤组分优于酶解液;酶解肽可以有效地保持鱼糜在冷藏期间的品质,超滤分离富集的〈5 k D的小分子肽显示出更好的抗氧化效果。
