罗非鱼皮蛋白多肽-Fe^(2+)结合物的制备及性质分析

Preparation and Characterization of Peptide-Fe_(2+)Complexes from Tilapia Skin Protein

以罗非鱼皮为原料,采用5种蛋白酶对其进行酶解,以罗非鱼皮酶解物多肽(tilapia skin protein peptides,TSPP)的Fe2+结合率为指标,筛选出Fe2+结合率最高的TSPP;探究结合时间、pH值、温度对结合率的影响以及TSPP结合Fe2+前后其荧光、紫外、红外等光谱的变化;对TSPP的分子质量分布、氨基酸的组成及其抗氧化活性进行测定。结果表明,罗非鱼皮蛋白经胰蛋白酶水解2 h后得到的TSPP,其Fe2+结合率最高;pH 5、温度37℃、时间90 min为最佳结合条件;TSPP结合Fe2+后,肽链发生折叠,其内源性荧光强度下降,紫外特征性吸收带出现红移,肽链中的氨基、羰基、羧基可能是Fe2+的结合位点;TSPP中的Fe2+结合活性肽,其分子质量大约在500~3000 Da之间,且肽链富含Asp、Glu、Gly、Arg及Pro等氨基酸;各酶解物均具有一定的抗氧化能力,TSPP结合Fe2+前后,其抗氧化能力无显著性变化;此外,虽然TSPP的抗氧化能力明显低于谷胱甘肽,但其Fe2+结合活性明显高于谷胱甘肽。结果显示,TSPP具有良好的Fe2+结合活性,有望发展为新型的铁元素膳食补充剂。

In this research,we optimized the preparation conditions of Fe2+-chelating peptides from tilapia skin protein,and we structurally characterize the complex.Five commercial proteases were screened for the highest Fe2+-chelating rate of peptides.The effects of chelating time,pH and temperature on the Fe2+-chelating rate were evaluated,and the changes in the fluorescence,ultraviolet and infrared spectra of the peptides were examined before and after chelating with Fe2+.In addition,the molecular mass distribution,amino acid composition and antioxidant activity of the peptides were measured.The results showed that the peptides obtained after 2 h of hydrolysis with trypsin had the highest Fe2+-chelating rate.The optimal chelating conditions were pH 5,37℃,and 90 min.Chelating with Fe2+resulted in folding of the peptide chain,decreased intrinsic fluorescence intensity,and red shift of the characteristic ultraviolet absorption band.Fe2+was likely bound to the amino,carbonyl and carboxyl groups of the peptides.The molecular mass of the Fe2+-chelating peptides was about 500–3000 Da,and the peptide chains were rich in Asp,Glu,Gly,Arg and Pro.All hydrolysates had antioxidant capacity.The antioxidant capacity was not significantly changed after chelating with Fe2+.Although the antioxidant capacity of the trypsinic hydrolysate was significantly lower than that of glutathione,the Fe2+-chelating activity was significantly higher than that of glutathione.The results showed that the peptides in the hydrolysate had excellent Fe2+-chelating activity suggesting the potential to be developed into a new dietary iron supplement.