摘要
以藏绵羊胎盘肽为研究对象,采用自由基清除、金属离子螯合和还原能力等方法分析不同浓度羊胎盘肽的抗氧化能力,并结合分子质量分布、氨基酸组成和结构表征分析探讨羊胎盘肽的抗氧化能力成因。结果表明,藏绵羊胎盘肽的抗氧化能力与其质量浓度呈正相关,有较强DPPH自由基和羟基自由基清除能力,IC 50值分别为2.83,0.94 mg/mL,与BHT能力相当;还具有一定的超氧阴离子自由基清除能力、螯合Fe 2+能力和Fe 3+、Cu 2+还原能力。羊胎盘肽中相对分子质量<1000 Da的寡肽含量接近90%,富含天冬氨酸、谷氨酸和甘氨酸等。酶解得到的羊胎盘肽仍保留源蛋白质特征官能团,微观形貌呈致密球状颗粒,蛋白质降解为肽的过程中分子发生重排和聚集,α螺旋结构减少,β-折叠和无规卷曲增加。适宜的小分子寡肽含量和氨基酸组成、特殊的微观形貌和空间结构赋予藏绵羊胎盘肽良好的抗氧化能力。
The free radical scavenging ability,metal ion chelation ability and reducing ability of different concentrations of placenta peptide from Tibetan sheep were determined,and the distribution of relative molecular weight,amino acid composition and structural characterization were also investigated to explain the causes of antioxidant capacity.The results showed that the antioxidant capacity of sheep placenta peptide was positively correlated with its concentration,and it had strong radical scavenging ability for DPPH·and·OH with IC 50 of 2.83 mg/mL and 0.94 mg/mL,respectively,which were comparable to BHT.In addition,the placenta peptide from Tibetan sheep also had certain O-2·scavenging ability,metal ion chelating ability for Fe 2+and reduction ability for Fe 3+and Cu 2+.Moreover,the placenta peptide below 1000 Da of molecular weight accounted for nearly 90%in total peptide,which contained an abundance of aspartic acid,glutamic acid,glycine and so on.Structural characterization results showed that the placenta peptide still remained the proper functional group structures of protein in sheep placental,the micromorphology of dense spherical granular happened,and the rearranged protein molecules aggregated during degradation of proteins to peptide.Based on the results of circular dichroism,the decreased content ofα-helices,increased content ofβ-sheets and random curl were observed.In a word,the placental peptide from the Tibetan sheep have nice antioxidant capacity due to its appropriate content of oligopeptides and amino acids profile,special micromorphology properties and space structure.
作者
任海伟
石菊芬
王曼琪
范文广
李志忠
REN Hai-wei;SHI Ju-fen;WANG Man-qi;FAN Wen-guang;LI Zhi-zhong(School of Life Science and Engineering,Lanzhou University of Technology,Lanzhou,Gansu 730050,China)
出处
《食品与机械》
北大核心
2020年第4期162-169,共8页
Food and Machinery
基金
陇原青年创新创业人才项目(编号:2019-39-GR28)
中国博士后科学基金(编号:2019T120961,2018M631217)
国家大学生创新创业训练计划项目(编号:DC201710731210)
甘肃省大学生创新创业训练计划项目(编号:DC2018140)。
关键词
藏绵羊
胎盘肽
分子质量分布
氨基酸组成
抗氧化能力
结构表征
Tibetan sheep
placental peptide
molecular weight distribution
amino acid composition
antioxidant capacity
structural characterization
