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测定了298.15K三种甘氨酰二肽(甘氨酰甘氨酸、甘氨酰-L-缬氨酸和甘氨酰-L-亮氨酸)在0.5,1.0,1.5和2.0mol·kg-1乙酸钠水溶液中的密度,计算了这些肽在乙酸钠水溶液中的表观摩尔体积,标准偏摩尔体积,标准偏摩尔转移体积,理论水化数和体积相互作用参数.结果表明:甘氨酰二肽的标准偏摩尔体积和标准偏摩尔转移体积均随乙酸钠浓度的增加而增大,溶液中离子与肽带电基团/甘氨酰基团(CH2CONH)之间的相互作用大于离子与肽的非极性基团间的相互作用,乙酸钠和甘氨酰二肽之间主要是对相互作用.利用共球交盖模型对所研究的肽与乙酸钠之间的体积相互作用进行了解释.利用氨基酸的标准偏摩尔体积值,对二肽的标准偏摩尔体积进行了估算,发现计算值与实验值一致.
Three glycyl dipeptides (glycylglycine, glycyl-L-valine and glycyl-L-leucine) at 298.15K were measured at 0.5, 1.0, 1.5 and 2.0 mol kg "1 Sodium acetate aqueous solution, the apparent molar volume, standard partial molar volume, standard partial molar transfer volume, theoretical hydration number and volume interaction parameters of these peptides in sodium acetate aqueous solution were calculated.The results showed that: The standard partial molar volume and the standard partial molar transfer volume of the peptide both increase with increasing sodium acetate concentration. The interaction between the ions in the solution and the peptide charged group / glycyl group (CH2CONH) is greater than that between the ion and the peptide The interaction between polar groups is mainly interaction between sodium acetate and glycyl dipeptide.The volume interaction between the studied peptide and sodium acetate is explained using a co-sphere lidding model. The standard partial molar volumes of amino acids were used to estimate the standard partial molar volumes of dipeptides. The calculated values agree with the experimental values.