为了探究阿胶的补血活性成分及其结构与功能之间的关系,该研究采用体外模拟消化和Ussing chamber吸收模型评价阿胶的铁螯合能力和促铁吸收作用,利用固定化金属亲和层析分离获得铁螯合肽,并鉴定阿胶肽及肽铁螯合物的物理性质和结构特征。结果表明,经胃肠两步消化后阿胶的铁螯合能力提高了16.22倍,表观渗透性增强,并能促进铁的吸收。阿胶铁螯合肽的分子质量集中分布在180~2 000 Da(含量为70.51%),质谱鉴定获得的4条肽序列为:GPAGPIGPV、LQGMPGERG、AGPPGADGQPGAK和LRGPRGDQGPVGRA,且铁离子主要与肽段氨基酸残基的羧基和氨基发生螯合,形成的螯合物发生折叠聚集后呈现相对致密的结构。该研究初步证明了阿胶在消化过程中产生的活性肽能够与铁离子发生作用,形成的肽铁螯合物可有效促进铁离子的吸收,具备潜在的机体补血活性,有助于科学评价阿胶的补血作用。
In this study, simulated digestion in vitro and chamber model were adopted to evaluate the ferrous iron-chelating capacity and iron absorption facilitation of Ejiao. The iron chelating ability of Ejiao increased by 16.22-fold after gastrointestinal digestion, with enhanced apparent permeability to improve iron absorption. After targeted isolation of Ejiao hydrolysates with iron chelating on immobilized metal affinity chromatography (IMAC), the Ejiao peptide-iron chelates were characterized by HPLC for molecular weight distribution and amino acid composition, LC-MS/MS for peptide sequences, fluorescence, and Fourier transform infrared spectroscopic analyses, scanning electron microscopy (SEM) analysis for structural and physical properties. The results demonstrated that Ejiao peptides chelated with ferrous iron mainly attributed to peptides with molecular weight ranging from 180-2 000 Da (70.51%). Four high-intensity peptides were sequenced as GPAGPIGPV, LQGMPGERG, AGPPGADGQPGAK and LRGPRGDQGPVGRA. The increased carboxylic and amino groups from acidic and basic amino acids in Ejiao peptide composition afforded more sites for iron chelation. The iron chelation aggregated to form larger particles. This study supports peptide-iron chelates formed during digestion to be one of the bioactive components of Ejiao and indicates the promotion of ferrous iron absorption as a potential hematopoietic mechanism of Ejiao.
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