Interaction of allylisothiocyanate with bovine serum albumin

The interaction of allylisothiocyanate with bovine serum albumin was monitored by “available” lysine estimation, electrometric and spectrophotometric titration, u.v. absorption and difference spectroscopy and electrophoresis. “Available” lysine estimation and electrometric titration indicated that the interaction increased with the reaction pH. Spectrophotometric titration indicated that at least two of the tyrosine groups became masked, probably via H-bonding, upon interaction of the protein with allylisothiocyanate. The pK_int values of the unreacted ?-amino groups of lysine and the titrable phenolic groups of tyrosine did not alter upon interaction. The electrophoretic mobility of the protein increased with the interaction. Difference spectral studies suggested thiourea formation.     

木犀草素、芹菜素与牛血清白蛋白相互作用的研究

目的研究木犀草素、芹菜素与牛血清白蛋白(BSA)的相互作用机制。方法主要应用荧光猝灭法及非辐射能量转移原理。结果测得不同温度下，木犀草素、芹菜素与牛血清白蛋白的结合常数，确定两种黄酮小分子对牛血清白蛋白荧光的猝灭是静态猝灭过程，并依据能量转移原理求得其结合距离和能量转移效率。结论木犀草素、芹菜素与牛血清白蛋白间有较强的结合作用，且结合力以疏水作用力为主；B(3′)-OH，B(4′)-OH邻位对黄酮与牛血清白蛋白的结合具有增强作用。     

应用荧光光谱法和紫外光谱法研究士的宁与牛血清白蛋白的相互作用

目的研究士的宁与牛血清白蛋白(BSA)的相互作用。方法采用荧光光谱法(FS)和紫外光谱法(UV)。结果确定了静态猝灭和非辐射能量转移是士的宁导致BSA荧光猝灭的主要原因；求得了士的宁与BSA之间的表观结合常数k_a分别为3.72×10³(27 ℃)，4.27×10³(37 ℃)，4.47×10³(47 ℃)；以及它们之间的结合位点数n为1.01±0.03；根据Frster非辐射能量转移机制求得给体与受体间的结合距离r为3.795 nm和能量转移效率E为0.033 8。结论牛血清白蛋白与士的宁分子间有结合作用，且结合力以疏水作用为主。     

荧光光谱法研究卡铂与牛血清白蛋白的相互作用

目的研究卡铂与牛血清白蛋白(BSA)在人体生理条件下的相互作用。方法采用荧光光谱法研究卡铂与BSA的荧光猝灭机制、结合位点数、结合常数;利用热力学参数考察其作用力类型;采用同步荧光光谱法探讨卡铂对BSA构象的影响。结果卡铂与BSA形成1∶1的复合物引起BSA的荧光猝灭,其猝灭类型为静态猝灭。卡铂与BSA结合位点数为9.81×103 mol/L,两者以疏水作用为主。卡铂与BSA相互作用使色氨酸残基所处的微环境发生改变。结论卡铂与BSA相互作用形成复合物,并改变BSA的构象。     

抗氧化活性藻蓝色素与牛血清白蛋白的相互作用

目的:进一步验证藻蓝色素(phycocyanobilin,PCB)的抗氧化作用,并研究藻蓝色素与牛血清白蛋白(bovine serum albu-min,BSA)之间的相互结合反应。方法:通过1,1-二苯基-2-苦基肼(1,1-diphenyl-2-picrylhydrazyl,DPPH)清除法验证PCB的抗氧化作用。用荧光光谱法、分光光度法研究了PCB与BSA的相互结合反应。结果:PCB对DPPH自由基的清除作用呈现一定的量效关系。随着PCB浓度的增加,BSA的荧光强度有规律地降低且呈良好的线性关系。结论:抗氧化活性PCB能够有效地淬灭BSA的内源荧光,该猝灭作用属于静态荧光猝灭作用,反应的结合常数K=1.22×106L.mol-1,结合位点数n=1.14,与PCB的结合基本不会引起BSA的构象变化。     

Interaction of isoliquiritigenin with bovine serum albumin studied by fluorescence quenching method

Interaction of ioliquiritigenin (ISL), which is the main active component of a commonly used traditional Chinese medicine (TCM) Glycyrrhiza uralensis Fisch. with bovine serum albumin (BSA) has been investigated. The quenching mechanism of fluorescence of bovine serum albumin by ISL was discussed. The binding sites number n and apparent binding constant K were measured by fluorescence quenching method. The thermodynamic parameters ΔH⁰, ΔG⁰, ΔS⁰ at different temperatures were calculated. The distance r between donor (bovine serum albumin) and acceptor (ISL) was obtained according to Förster theory of non-radiation energy transfer. The results of synchronous fluorescence spectra and UV-vis absorption spectra show that the conformation of bovine serum albumin has been changed.     

Complexation of cox-2 inhibitors with bovine serum albumin: Interaction mechanism

Mechanism of interaction of six cox-2 inhibitors – celecoxib, valdecoxib, etoricoxib, parecoxib sodium, meloxicam and nimesulide – with bovine serum albumin (BSA) was studied using fluorescence spectroscopic technique. Results were discussed in terms of the binding parameters, thermodynamics of the binding process, the nature of forces involved in the interaction and the fluorescence quenching mechanism involved. Association constants were of the order of 10⁴–10⁵ for various drugs. Binding affinity varied with the nature of drug. Nature of forces involved in the interaction could be predicted from the thermodynamic parameters for the binding. Meloxicam and nimesulide shared common sites with hydrophobic probe, 1-anilinonaphthalene-8-sulfonate (ANS) on BSA molecule. Stern-Volmer analysis of the quenching data indicated that both tryptophan residues of BSA are fully accessible to the drugs and predominantly static quenching mechanism is involved in the interaction.     

白皮杉醇与牛血清白蛋白相互作用的研究

目的应用荧光光谱法和紫外光谱技术对白皮杉醇（piceatann01）与牛血清白蛋白（BSA）之间的相互作用进行研究。方法计算白皮杉醇与BSA的结合常数K、结合位点数及热力学函数△G、△S、△H,分析白皮杉醇对BSA的荧光淬灭过程及其与BSA的相互作用类型;运用Foerster’S偶极．偶极非辐射能量转移原理测定了白皮杉醇与BSA的结合距离。结果随着白皮杉醇浓度升高,BSA内源荧光强度有规律的下降;随温度的升高,静态淬灭常数和结合常数均下降;热力学函数△G〈0、△S〉0、△H〈0。结论白皮杉醇对BSA的荧光淬灭属于自发的以疏水作用力为主导的非辐射能量转移的静态淬灭过程。     

荧光光谱法研究柚皮苷与牛血清白蛋白的相互作用

目的采用荧光光谱技术研究柚皮苷与牛血清白蛋白(BSA)的相互作用。方法根据295、303、310、315K温度下柚皮苷对BSA的荧光猝灭作用,利用Stern-Vol mer方程及双倒数方程处理实验数据,采用同步荧光光谱探讨柚皮苷对BSA构象的影响。结果柚皮苷与BSA间的结合常数(Kb)分别为5.79×105L(295 K)、2.74×108(303 K)、2.48×106(310 K)、1.28×108(315 K),柚皮苷与BSA结合的热力学参数△rHm>0、△rSm>0和△rGm<0。结论柚皮苷对BSA的荧光猝灭过程以静态猝灭为主,两者主要靠疏水作用力相结合,结合过程为自发反应过程。     

抗凝药物华法林与牛血清白蛋白相互作用光谱研究

采用紫外-可见吸收光谱和荧光光谱，在生理pH条件下，研究华法林与牛血清白蛋白的相互作用。探讨华法林对于牛血清白蛋白的荧光猝灭机制。结果表明华法林对牛血清白蛋白的猝灭作用为动态猝灭过程。猝灭常数在16 ℃和37 ℃分别为6.05×10⁴ L·mol^-1和6.14×10⁴ L·mol^-1。根据Fster的偶极-偶极无辐射能量转移理论，求得牛血清白蛋白-华法林的能量转移效率E为0.37，两者间的最近距离r为3.15 nm。     

Interaction of benzodiazepine derivatives with bovine serum albumin—II: Circular dichroism studies

The interaction of benzodiazepine derivatives with bovine serum albumin (BSA) was studied by circular dichroism (CD) measurements. Most of the investigated benzoidiazepines show biphasic extrinsic Cotton effects, which are largely influenced by raising pH from 6.60 to 8.20. Quantitative estimation of the CD data pointed out that there are several binding sites on the BSA molecule. The CD data do not differ very much from those found for the interaction of the drugs with human serum albumin (HSA). Therefore it is suggested that at least a part of the benzodiazepine binding sites on the BSA molecule has similar properties to the single binding site on the HSA molecule. The extrinsic Cotton effects of the benzodiazepines in the presence of BSA are influenced by fatty acids and sodium dodecyl sulfate in a similar way as by the pH-value of the solution. This is explained by a similar influence of the substances and of pH on the protein conformation.     

大黄素甲醚和牛血清蛋白相互作用的电化学性质研究

在pH4.0的Britton-Robinson(B-R)缓冲体系中,应用循环伏安法和示差脉冲伏安法对大黄素甲醚与牛血清白蛋白(BSA)相互作用的电化学性质进行研究。结果表明,二者结合生成了一种非电活性的超分子化合物,同时对结合反应的机理进行了探讨。BSA的存在导致大黄素甲醚氧化还原峰电流降低,峰电位基本不变,峰电流的下降值同所加入的BSA浓度在一定范围内呈线性关系。线性范围5.0×10-6~1.0×10-7mol/L,检出限3×10-7mol/L。     

Interaction of cimetidine with human serum albumin

Ultrafiltration studies have detected the existence of a weak interaction between cimetidine and human serum albumin, a finding supported by corresponding studies with this xenobiotic and bovine serum albumin. Furthermore, the binding characteristics of the interaction with human serum albumin (4 sites, K = 630 M-1) more than suffice to account for the proportion of protein-bound drug in the serum of patients subjected to cimetidine therapy. Thus, although alpha 1-acid glycoprotein is usually regarded as the specific transporter of basic drugs, the present evidence implicates albumin as the likely binding protein for cimetidine in serum.     

人血清白蛋白与4种黄酮类化合物相互作用研究

目的研究4种黄酮化合物与人血清白蛋白(HSA)的相互作用,探究黄酮化合物结构差异对其与体内大分子蛋白质结合的影响。方法用荧光光谱法研究4种黄酮化合物与HSA的结合反应,判断其荧光猝灭类型,计算得到猝灭常数、结合位点与相关热力学参数等。结果 4种黄酮化合物均可引起HSA荧光不同程度的猝灭;随着温度升高,猝灭常数与结合常数均降低;结合位点数在1左右;热力学参数ΔH<0,ΔS>0,ΔG<0。结论 4种化合物对HSA的猝灭以静态猝灭为主;与HSA之间的结合反应均可自发进行;作用力以静电引力为主;推测黄酮类化合物主要通过羟基与HSA相互作用,而甲氧基与HSA的结合力略小于羟基。