Cardiano Paola, Giacobello Fausta, Giuffrè Ottavia, Sammartano Silvio
Dipartimento di Scienze Chimiche, Biologiche, Farmaceutiche ed Ambientali, Università di Messina, Viale F. Stagno d'Alcontres 31, 98166 Messina, Italy.
Dipartimento di Scienze Chimiche, Biologiche, Farmaceutiche ed Ambientali, Università di Messina, Viale F. Stagno d'Alcontres 31, 98166 Messina, Italy.
Biophys Chem. 2017 Nov;230:10-19. doi: 10.1016/j.bpc.2017.08.001. Epub 2017 Aug 8.
In this paper a thermodynamic and spectroscopic study on the interaction between Al and glycine (Gly), l-cysteine (Cys), tranexamic acid (Tranex) is reported. Speciation models have been obtained by processing potentiometric titration data to determine stability constants of the species formed in aqueous solution at T=298.15K, 0.15≤I/molL≤1 in NaCl. Thermodynamic formation parameters have been obtained from calorimetric titration data, at T=298.15K, I=0.15molL using NaCl as ionic medium. Al-Cys system was also investigated by spectrophotometric and H NMR measurements. H NMR experiments were performed on Al-Tranex system as well. Different speciation models have been observed for the three systems. The results showed the formation of MLH, ML and ML(OH) species for Gly, ML, ML and MLOH for Cys, MLH and MLOH for Tranex. The formed species are quite stable, i.e. for ML, logβ=7.18, 11.91 for Gly and Cys, respectively, at I=0.15molL and T=298.15K. For all the systems the dependence of formation constants on ionic strength over the range 0.1-1molL is reported. The sequestering ability of the ligands under study was also evaluated by pL empiric parameter. For Gly, Cys and Tranex, pL=2.51, 3.74, 3.91 respectively, at pH=5, I=0.15molL and T=298.15K.
本文报道了对铝与甘氨酸（Gly）、L-半胱氨酸（Cys）、氨甲环酸（Tranex）之间相互作用的热力学和光谱研究。通过处理电位滴定数据获得了物种形成模型，以确定在T = 298.15K、0.15≤I/molL≤1的NaCl水溶液中形成的物种的稳定常数。在T = 298.15K、I = 0.15molL以NaCl作为离子介质的条件下，从量热滴定数据中获得了热力学形成参数。还通过分光光度法和核磁共振氢谱测量研究了铝-半胱氨酸体系。对铝-氨甲环酸体系也进行了核磁共振氢谱实验。观察到这三个体系有不同的物种形成模型。结果表明，甘氨酸形成了MLH、ML和ML(OH)物种，半胱氨酸形成了ML、ML和MLOH物种，氨甲环酸形成了MLH和MLOH物种。形成的物种相当稳定，即在I = 0.15molL和T = 298.15K时，对于ML，甘氨酸和半胱氨酸的logβ分别为7.18和11.91。报道了所有体系中形成常数在0.1 - 1molL范围内对离子强度的依赖性。还通过pL经验参数评估了所研究配体的螯合能力。在pH = 5、I = 0.15molL和T = 298.15K时，甘氨酸、半胱氨酸和氨甲环酸的pL分别为2.51、3.74和3.91。
