摘要
背景:金属离子与生物分子在溶液中可导致催化、电子转移、氧气运输等一系列的化学过程,近年来国内外对金属离子与氨基酸作用的研究,涉及Cu+和Cu2+-氨基酸的较为广泛,对L-亮氨酸与银(I)离子反应机制的研究还较为贫乏。目的:用紫外/可见光谱和荧光光谱考察L-亮氨酸同银(I)离子间的相互作用。设计、时间及地点:金属离子与氨基酸水平光谱检测实验,于2004-09/2006-07在贵州大学完成。材料:L-亮氨酸由解放军第二军医大学药学系合成药物研究室提供,硝酸银为重庆无机化学试剂厂生产。UV-265型紫外分光光度计、RF-540荧光分光光度计为日本岛津产品。光源为150W的氙灯,激发和发射狭缝宽度均为10nm,为美国Orion公司产品。方法:向刻度离心管中依次加入0.02mol/L的L-亮氨酸溶液3.6mL,0.03mol/LAg(NH3)2NO3溶液0.8mL,1%三羟甲基氨基甲烷缓冲溶液1.2mL,4%十二烷基硫酸钠溶液0.4mL和0.1%HCHO溶液1.0mL,用HCl或NaOH调节pH值至7.06左右,震荡均匀后,反应90min,加12%醋酸1.5mL终止反应,最后终体积为10mL,即为L-亮氨与银(I)离子的配合物。主要观察指标:应用紫外/可见光谱和荧光光谱分析L-亮氨酸与银(I)离子的相互作用。结果:pH电位滴定法测定L-亮氨酸的离解常数为9.29,半n_法求得各L-亮氨酸-Ag配合物的逐级稳定常数为lgK1=11.04,lgK2=10.97。L-亮氨酸-银(I)离子体系的吸收峰发生明显红移,400nm^500nm区域的吸收呈现出宽而平滑的带,该体系受紫外光的影响大于可见光的影响,荧光强度随光照度的增加而不断减小。反应体系紫外/可见光谱的Soret带随溶液pH值的变化而改变,在光照度700Lux左右时其Soret带才出现吸收,且随光照度的增大、光照时间的增加其吸收也相应增强,荧光猝灭程度也越大。20℃L-亮氨酸-银(I)离子体系的电动电位为1.29×10-4V,动态猝灭常数为1.99×102L/mol,荧光猝灭速率常数为0.199×1011L/(mol·s)。�
BACKGROUND： Metal ions in solution with bimolecules cause a series of chemical processes such as catalysis, electron transfer, O2 transport and stabilization, etc. Recently, investigations on the interaction of metal ions to amino acids are quite widespread, mainly invloving the interaction of Cu^＋ and Cu^2＋-amino acids. It is an absence that the research of the mechanism for interaction of leucine with silver （I） ion. OBJECTIVE： To study the interaction of silver （I） ion with leucine by using UV/visible spectrum and fluorescence spectra. DESIGN, TIME AND SETTING： Levels of metal ions and amino acids were detected in the Guizhou University from September 2004 to July 2006. MATERIALS： Leucine was offered by Synthetic Drug Research Room, Pharmacy Department, and the Second Military Medical University of Chinese PLA. AgNO3 was produced by Chongqing Inorganic Chemistry Factory. UV-265 UV speetrophotometer and RF-540 spectrofluorometer were both produce by Shimadzu Company （Japan）. Xenon lamp at 150 W was produced by Orion Company （USA）, excitation and emission slit-width were 10 nm. METHODS： The graduated centrifuge tube was added with 3.6 mL leucine solution （0.02 mol/L）, 0.8 mL Ag（NH3）2NO3 （0.03 mol/L）, 1.2 mL 1% Tris buffer solution, 0.4 mL 4% sodium dodecyl sulfate, and 1.0 mL 0.1% HCHO solution. Then pH values were adjusted with HCl or NaOH to 7.06, and reacted for 90 minutes after the vibration had been fairly well-distributed, finally, 1.5 mL 12% acetic acid was added to stop reaction and made the final volume up to 10 mL, which was the compound of leucine with silver （I） ion. MAIN OUTCOME MEASURES： The interactions of leucine with silver （I） ion were characterized by means of UV/visible spectrum and fluorescence spectra. RESULTS： Applied pH potentiometric determination, we obtained that the dissociation constants of lencine were pKa（Leu）=9.29 and half n determination showed the stepwise stability constants of leucine-silver （I） as follows： lgK1=1
出处
《中国组织工程研究与临床康复》
CAS
CSCD
北大核心
2008年第36期7071-7075,共5页
Journal of Clinical Rehabilitative Tissue Engineering Research
