【摘要】 应用pH电位滴定法研究了三元配合物Co(L phe)(Aa)[L phe为苯丙氨酸根,Aa-为L val(缬氨酸根)、L leu(亮氨酸根)、L ile(异亮氨酸根)或L trp(色氨酸根)]在水溶液中的稳定性[t=25℃,c(NaClO4)=0 1mol/L].三元配合物相对稳定性用δK[δK=ΔlogK-ΔlogKS,其中ΔlogK=logKCoCo(L phe)(Aa)-logKCoCo(L phe)-logKCoCo(Aa),ΔlogKS=1/2(ΔlogK(L phe)+ΔlogK(Aa)+log2)]表示 结果表明:与相关L-丙氨酸(L ala)配合物Co(L phe)(L ala)相比,所有这些配合物均具有相对较高的δK值,表明配合物分子内存在着额外的稳定化作用.这种稳定化作用可能主要归因于三元配合物分子内氨基酸侧链之间的疏水作用,并且这种作用随着氨基酸侧链结构变化而变化.更多还原

【Abstract】 Stability constants of ternary complexes Co（L-phe）（Aa） was determined by pH potentiometric titrations in water, where L-phe^-=L-phenylalaninate, Aa^-=L-valinate, L-leucinate, L-isoleucinate, and L-tryptophanate and [t = 25　℃, c（NaClO₄） = 0.1 mol/L]. The relative stability of the ternary complexes was defined by δ_K[δ_K =ΔlogK-ΔlogK_S, where （）ΔlogK=logK^Co_{Co（L-phe）（Aa）}-logK^Co_{Co（L-phe）}-logK^Co_Co（Aa）, and （）ΔlogK_S = 1/2(ΔlogK_（L-phe）+ΔlogK_（Aa）+log2)]. The results showed that, compared with the complex Co（L-phe）（L-ala） with L-alaninate, the complexes with the amino acids have larger δ_K values, indicating that there are extra stabilizing effects in the ternary complexes. This may be mainly attributed to the intramolecular hydrophobic or stacking interactions between the phenyl group of L-phe and the side chains of other amino acids in the complexes, the interactions varying with the side chains of the amino acids.更多还原