玉米低聚肽螯合铁（II）的制备和结构表征

以玉米低聚肽和氯化亚铁为原料制备玉米低聚肽螯合铁（II），以得率和螯合率评价螯合效果，通过单因素实验、响应面中心组合设计和验证实验确定最佳工艺。通过高效液相色谱仪（HPLC）测定玉米低聚肽螯合铁（II）的氨基酸组成，并通过傅里叶变换红外光谱（FTIR）和扫描电镜（SEM）对玉米低聚肽螯合铁（II）的结构进行表征。结果表明，玉米低聚肽螯合铁（II）的最佳制备工艺为肽盐比5:1，pH7.0，螯合时间35 min，螯合温度65 ℃。此条件下，玉米低聚肽螯合铁（II）的得率为46.59%±1.69%，铁（II）的螯合率为51.75%±2.10%。玉米低聚肽螯合铁（II）中必需氨基酸含量占比25.58%，相对分子质量小于1000 u的组分占比高达89.77%。FTIR结果表明，铁（II）与玉米低聚肽末端羧基或氨基中的氮原子、氧原子形成配位键，从而形成螯合物；SEM结果显示，螯合后分子发生聚集，圆球状结构消失，说明成功生成了一种新型玉米低聚肽铁螯合物。

Preparation and Structure Characterization of Iron(II)-Chelating Corn Oligopeptides

Corn oligopeptides and ferrous chloride were used as raw materials to prepare iron (II)-chelating wheat oligopeptides. The chelating effect was evaluated by yield and chelating rate, and the best process was studied by single-factor, response surface centered design and verification experiments. The amino acid composition of iron(II)-chelating corn oligopeptides was determined by high performance liquid chromatography (HPLC), the structural characteristics of corn oligopeptides before and after chelating were analyzed by Fourier transform infrared radiation (FT-IR) and scanning electron microscope (SEM). The results showed that the optimum preparation conditions of iron (II)-chelating corn oligopeptides were as follows: Mass ratio between corn oligopeptides and ferrous chloride 5:1, pH7.0, chelating time 35 min, and chelating temperature 65 ℃. Under the conditions, the yield was 46.59%±1.69% and the iron (II) chelating rate was 51.75%±2.10%. The content of essential amino acids in iron(II)-chelating corn oligopeptides accounted for 25.58%, and the components with relative molecular weight less than 1000 u accounted for as high as 89.77%. FTIR analysis results showed that iron (II) formed coordination bonds with nitrogen and oxygen atoms in the terminal carboxyl or amino group of the corn oligopeptides to form iron (II)-chelating corn oligopeptides. SEM results showed that after chelating the molecules aggregated and the spherical structure disappeared, indicating that a new type of iron(II)-chelating corn oligopeptides was successfully formed.