Design And Synthesis Of Fluorescence Probe For Zinc Detection

Zinc is the second most abundant heavy metal ion after iron, which plays an important role in various biological processes. About 58~91% of zinc presents as soluble form in plant. The physiological functions of zinc include the effect of zinc on the metabolisms of carbohydrate, enzyme, protein, fatty acids, nucleic acid and auxin. At the same time, it plays great roles on the structure and function of biomembrane, free radicals, gene transcription and expression , apoptosis and so on.In 1987, N-(6-Methoxy-8-quinolyl)-P-toluenesulfonamide (TSQ) was the first fluorescent probe to be developed for Zn2+ : From that time on, several fluorescent sensors for Zn2+ have been described, such as Zinquin, Zinpyr-1, ACF-1, ACF-2, Newport Green. The importance of zinc-specific fluorescent probes is particularly apparent in exploring zinc function, properties and combination in various biological processes. It would provide additional insight into the cell biology of zinc. However, the detection of free zinc in living cells still has always been problematic.The amino acid histidine and cysteine are the most frequently occurring ligands of zinc in physiological processes. The purpose of this paper is to obtain information on the fluorescence behavior of zinc complexes with "natural" histidine-containing or cysteine-containing ligands. The experimental method includes selecting pure complexes of histidine-containing or cysteine-containing materials, from C- and N-terminal group of these amino acids to link to a group which have color or fluorescence or ultraviolet absorption, elucidating their binding affinity, fluorescence or UV-visible spectrum properties with zinc at physiological concentration and to elucidate their structure in the solid state via Infrared spectroscopy. With the help of the concernedthe data, the analysis was done to prove whether it can be applied to the zinc detection, in other words, whether it can be used as a new fluorescence probe for zinc detection.The results show that: four histidine derivatives from C- terminal were synthesized which is based on the forming peptide bonds, and obtained 58-73% of compounds from Boc-His(Tos)-OH. Histidine and cysteine derivatives can coordinate with zinc, but the UV or fluorescence spectral changes are not significant enough to allow effective detection of zinc in plant system.