Preparation and Characterization of a Novel Ala-Gin Dipeptide-Zn~(2+) Complex

摘要

Peptide-trace elements complex with constant coordination ratio and high biological activity has drawn wide attention around the world. The aim of the present study was to synthesize and characterizes Ala-Gin dipeptide-Zn~(2+) complex as an oral medicine. A freeze-dry powder containing Ala-Gin dipeptide and Zn~(2+), of which a chelating ratio of the dipeptide to Zn~(2+) is 2 to 1, was obtained in this study. Cyclic voltammetry analysis showed that ZnSO4 has only cathodic peak, while the dipeptide and the complex have both cathodic and anodic ones. The analysis of the complex by differential thermal analyzer showed that a new endothermic peak at 537.3 °C appeared. It may be deduced that the coordination bond between carbonyl oxygen and Zn~(2+) broke. The endothermic peak at 279.5 °C belonged to ionic bond fission between the carboxyl oxygen and Zn~(2+) Infrared analysis of the complex showed that absorption at 3334 cm~(-1) disappeared, which belonged to hydroxyl hydrogen of carboxylic acid. These characteristics suggested that an ionic bond formed between the carboxyl group of C8 and Zn~(2+), and the carbonyl oxygen in amide plane of C4 and carbonyl oxygen of carboxyl of C8 formed coordinate bond with Zn~(2+), respectively, providing lone pair electrons to the p empty orbital of Zn~(2+). Quantitative and biological qualitative evaluations showed that this Ala-Gin dipeptide-Zn~(2+) complex may serve as an effective oral medication for adsorption of the peptide and Zn~(2+) simultaneously in vivo.