Noszál B, Kassai-Tánczos R
Department of Inorganic and Analytical Chemistry, L. Eötvös University, H-1518 Budapest 112, Pf. 32, Hungary.
Talanta. 1991 Dec;38(12):1439-44. doi: 10.1016/0039-9140(91)80293-9.
Three and two protonation macroconstants as well as twelve and four microconstants have been determined for arginine and citrulline, respectively. These data include microscopic basicity values of the arginine guanidino group, for which no reliable constants have been reported earlier. The determinations were carried out by a combination of potentiometric and deductive methods. The guanidino basicity proved to be extremely high, and can be characterized by microconstants between 14.7 and 15.0 log k units. The interactivity parameters could also be determined from the microscopic protonation constants. These values for the guanidino-amino and the guanidino-carboxylate interactions are 0.2 and 0.1 log k units, respectively. The pH-dependent distribution of all eight arginine microspecies is made visual by a microspeciation diagram. The microspeciation diagram is the most useful tool to predict bidentate binding isomerism in metal complex formation and site-specific bioligand-bioligand associations.
已分别测定出精氨酸和瓜氨酸的三个和两个质子化宏观常数以及十二个和四个微观常数。这些数据包括精氨酸胍基的微观碱度值，此前尚未报道过其可靠常数。测定采用电位滴定法和演绎法相结合的方式进行。结果表明胍基碱度极高，可用14.7至15.0 log k单位之间的微观常数来表征。相互作用参数也可由微观质子化常数确定。胍基-氨基和胍基-羧酸盐相互作用的这些值分别为0.2和0.1 log k单位。通过微观物种形成图可以直观地呈现所有八种精氨酸微观物种的pH依赖性分布。微观物种形成图是预测金属配合物形成中的双齿结合异构现象以及位点特异性生物配体-生物配体缔合的最有用工具。
