Studies on the Interaction of Hemoporphyrin Metalporphyrin and Levo Dopa
LI Wen-juan1,ZHANG Yong2*,YAN Xin-liang2
1. Department of Chemistry of Shanxi Normal University,Taiyuan 030012,China 2. College of Chemistry and Chemical Engineering of Shanxi University,Taiyuan 030006,China
Abstract：Levo dopa (L-DOPA) is a prodrug that is converted to dopamine by DOPA decarboxylase and can cross the blood-brain barrier. When in the brain,levo dopa is decarboxylated to dopamine and stimulates the dopaminergic receptors,thereby compensating for the depleted supply of endogenous dopamine seen in Parkinson’s disease. So,Levodopa is a medication used to treat Parkinson’s disease clinically. In the present paper the interaction of hematoporphyrin and levo dopa was studied by fluorescence at different temperature in the quenching experiments. The excitation fluorescence spectrum of levo dopa displayed a peak at 282 nm and that for the emission fluorescence spectrum was at 320 nm in pH 7.4 buffer solution. The intensity of the fluorescence was effectively quenched as the hemoporphyrin concentration increased and the emission spectra blue-shifted with the isosbestic point appearing,indicating that the interaction between hematoporphyrin and levo dopa occurred and a new complex was formed. According to Stern-Volmer equation and Lineweaver-Burk double-reciprocal equation,the thermodynamic parameters,formation constants and some other concerned constants were obtained. The quenching rate constants Kq bigger than 2.0×1010 L·mol-1·s-1 were found. So the kinetic behavior of the reaction between hematoporphyrin and levo dopa was suggested to be static fluorescence quenching model. In addition,with the temperature increasing,the formation constants decreased to some extent. At 25 ℃,ΔG＝-26.58 kJ·mol-1;ΔS＝138.7 J·K-1 and ΔH=14.71 kJ·mol-1.
李文娟1,张勇2*,燕新梁2 . 血卟啉与左旋多巴相互作用的研究[J]. 光谱学与光谱分析, 2007, 27(08): 1611-1614.
LI Wen-juan1,ZHANG Yong2*,YAN Xin-liang2. Studies on the Interaction of Hemoporphyrin Metalporphyrin and Levo Dopa. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2007, 27(08): 1611-1614.
