血红蛋白肽分子量分布对血红素酸溶性的影响及其相互作用研究

Heme in hemoglobin is an excellent source of iron while its monomer is insoluble in acid environment of stomach. The acid solubility of heme could be improved by hydrolysing hemoglobin and controlling corresponding molecular weight distribution. In this study, hemoglobin peptides with different molecular weight distributions were obtained by two-step enzymatic hydrolysis and ultrafiltration method. The relations between ultrafiltration conditions, peptide molecular weight distributions and acid solubility of heme were investigated. Furthermore, the interaction force, binding constant and bond force between peptide and heme were explored by fluorescence spectroscopy. The results showed that acid-soluble percentages of heme achieved 84.1% when the protein concentration in light-degree hydrolysates during ultrafiltration is 22.5mg/ml and the mass ratios of protein in ultrafiltration liquid to heme in high-degree hydrolysates was 1.15. Peptide with the molecular weight is less than 1kDa weakened the heme acid solubility, whereas peptide with the molecular weight in the range of 1k-2kDa may be the key to improve the acid solubility of heme. Fluorescence spectroscopy showed that the quenching type between heme and peptide was static quenching, the main interaction force is possibly hydrophobic interactions, forces which can cause enthalpy change such as coordination bond, Van der Waals forces and hydrogen bonding play an supporting role.