脱盐咸鸭蛋清肽-亚铁螯合物的制备及表征

本文以脱盐咸鸭蛋清肽为原料,Fe Cl₂·4H₂O为铁源,以亚铁的螯合率和螯合物的得率为跟踪指标,对鸭蛋清肽-亚铁螯合物的制备条件进行优化;并采用红外光谱、动态光散射仪、荧光光谱、圆二色谱手段,对肽-亚铁螯合物进行了结构表征。单因素及正交实验结果表明,鸭蛋清肽-亚铁螯合物的最佳螯合反应条件:抗坏血酸（VC）与亚铁盐的质量比为0.2∶1,鸭蛋清肽溶液的浓度为4%,肽与亚铁盐的质量比为3∶1,p H 5.5,反应温度为40℃,反应时间为40 min,乙醇的添加量为反应液体积的7倍,在此条件下亚铁的螯合率为65.15%,螯合物得率为44.46%。红外光谱显示Fe²⁺与肽的氨基端与羧基端相结合;荧光光谱表明随着Fe²⁺的增加,荧光吸收带从3822 nm显著下降为3124.44 nm（p<0.05）;激光粒度仪显示肽与肽-亚铁螯合物的半径分别为（144.23±5.86）nm和（453.66±8.74）nm;圆二色谱显示肽中α螺旋、β折叠的含量为28.66%±1.54%、10.02%±1.04%,而肽-亚铁螯合物中α螺旋、β折叠的含量为16.10%±1.96%、27.33%±1.08%,两者均发生显著变化（p<0.05）。从结构层面证实了肽-亚铁螯合物的形成。 

Preparation and characterization of desalted duck egg white peptide-ferrous chelate

In this paper, desalted duck egg white peptides and Fe Cl₂·4H₂O was used as the raw material.Using chelating rate of ferrous and the yield of chelate as trace indexs, the preparation conditions of duck egg peptides-ferrous chelate were optimized, and the structure of peptides-ferrous chelate was characterized by IR, dynamic light scattering, fluorescence spectroscopy and circular dichroism.The results of single factor and orthogonal test showed that the optimal chelating reaction condition of duck egg white peptides-ferrous chelate was as follows: the mass ratio of VCto ferrous salt was 0.2∶ 1, the concentration of duck egg peptides was 4%, the ratio of peptides to ferrous salt was 3 ∶ 1, the p H value was 5.5, the temperature was 40 ℃, the reaction time was 40 min, and the amount of ethanol was 7 times of the volume of the reaction solution. Under these conditions, the chelating rate of ferrous was 65.15%, and the yield of the chelate was 44.46%.The Infrared spectrum showed that Fe²⁺ binds to the amino terminus and the carboxyl terminal of peptide.The fluorescence spectrum showed that the fluorescence absorption band decreased from 3822 nm to 3124.44 nm with the increase of Fe²⁺ ( p < 0.05) .The laser particle size analyzer showed that the radius of peptide and peptide-ferrous chelate was ( 144.23 ± 5.86) nm and ( 453.66 ± 8.74) nm respectively.The circular dichroism showed that the content of α-helix in the peptide was 28.66% ± 1.54% and 10.02% ± 1.04%, while the content ofα-helix and β-sheet in peptide-ferrous chelate was 16.10% ± 1.96% and 27.33% ± 1.08%, both of which had changed significantly ( p < 0.05) .The formation of peptides-ferrous chelate was confirmed from the structural.