尼古丁与BSA相互作用的光谱研究

用紫外-可见光谱和荧光光谱研究了尼古丁与牛血清白蛋白(bovine serum albumin, BSA)的相互作用。荧光研究表明,尼古丁浓度的增加引起BSA 345 nm处荧光有规律地猝灭。Stern-Volmer 方程分析pH 5.0,pH 7.4和pH 11.0体系的荧光猝灭机理发现,pH 5.0体系属动态猝灭,而pH 7.4和pH 11.0体系为静态猝灭。Lineweaver-Burk双倒数方程计算pH 7.4和pH 11.0体系在温度为20和37 ℃条件下尼古丁和BSA的结合常数k分别为：k_{20 ℃}=140.15 L·mol-1 ,k_{37 ℃}=131.83 L·mol-1 (pH 7.4)和k_{20 ℃}=141.76 L·mol-1,k_{37 ℃}=27.79 L·mol-1(pH 11.0),表明结合常数在pH 7.4条件下受温度的影响要比pH 11.0条件下小,推测是由于不同pH下尼古丁存在的不同形态所致。紫外-可见光谱研究表明,pH 7.4条件下尼古丁浓度的增加引BSA在210 nm处吸收峰吸收强度减小且红移,说明BSA二级结构发生变化,即螺旋结构变松散;紫外二阶导数光谱和同步荧光光谱(Δλ=λ_em-λ_ex=15 nm和Δλ=λ_<i>em-λ_ex=60 nm)分析尼古丁对BSA芳香性氨基酸(Trp, Tyr和Phe)残基微环境的变化,结果表明高浓度的尼古丁使所有这些芳香性氨基酸残基微环境由疏水环境转变为亲水环境。     

头孢他啶与牛血清白蛋白(BSA)的相互作用

采用荧光、紫外及红外光谱法研究了头孢他啶与牛血清白蛋白(BSA)的结合反应.头孢他啶对BSA的色氨酸残基和酪氨酸残基均具有猝灭作用,其猝灭机理为静态猝灭,两者之间形成新的复合物是导致BSA荧光猝灭的主要原因.获取了复合物的结合常数(298K:1.27×10~4L·mol~(-1);310K:1.33×10~41·mol~(-1)).BSA Ⅱ A结构域的site I位点是其唯一可能结合位点.同步荧光光谱表明头孢他啶造成BSA的酪氨酸残基的极性增强.红外光谱表明头孢他啶引起了BSA二级结构的改变,使其α-螺旋含量降低.     

几种EGCG金属配合物与牛血清白蛋白的相互作用

运用荧光光谱法研究了几种EGCG金属配合物(EGCG-M)与牛血清白蛋白(BSA)的相互作用。实验结果表明,几种EGCG-M对BSA的荧光光谱有明显猝灭作用,两者之间的相互作用为静态猝灭,并得到了静态猝灭常数、结合常数及结合位点数等数据。     

Colorimetric detection of sodium ion in serum based on the G-quadruplex conformation related DNAzyme activity

There has been a big challenge in developing the Na⁺ sensor that can be practically used in the physiological system with the interference of large amounts of K⁺. In this research, a novel Na⁺ sensor has been designed based on the G-quadruplex-conformation related DNAzyme activity. The sensor exhibits high selectivity and sensitivity with the detection limit of 0.6 μM, which enables the sensor to be practically used in determination of the Na⁺ level in serum. The research not only provides a simple Na⁺ sensor but also opens a new way for developing the detection technology of Na⁺.     

Molecular Docking approach on the effect of Site- Selective and Site-Specific Drugs on the Molecular Interactions of Human Serum Albumin (HSA) -Acridinedione dye complex

Molecular Docking (Mol.dock) of resorcinol based acridinedione dyes (ADR1 and ADR2) with a globular protein, Human Serum Albumin (HSA) were carried out. Docking studies reveal that ADR2 dye binding with HSA is energetically more stable and feasible than ADR1 dye. ADR1 dye predominantly resides in site I and III of HSA rather than binding site II wherein, ADR1 dye acts as hydrogen bonding (HB) acceptor through its carbonyl oxygen. On the contrary, ADR2 dye resides in all the binding sites of HSA such that the dye acts as the HB donor through the NH hydrogen atom and the carbonyl oxygen of the amino acid acts as the HB acceptor. The stability of dye-protein complex in the presence of several non-steroidal anti-inflammatory drugs (NSAIDs) was carried out by employing specific site selective drugs (Sudlow binding site drugs). The energetics and the bimolecular interactions of various drugs with ADR1-HSA and ADR2-HSA were generated to ascertain the influence of drug and its governance on the binding affinity of dye-protein complex. Sudlow site I binding drugs were effective in decreasing the energetics of ADR1 dye-HSA complex whereas site II binding drugs predominantly decreases the affinity of ADR2 dye with HSA. However, the dyes efficiently displaces the site specific drugs from their specific binding sites of HSA which was not observed in the case of drugs on the displacing ability over dyes situated in different domains of protein. Mol.dock studies are employed as an authentic, reliable and most effective tool to ascertain the binding stability of host–guest complex as well as to ascertain the most probable location of several competing ligands in various domains of HSA.