Cd（Ⅱ）与HSA或BSA的结合平衡研究

用平衡透析法详细研究了生理pH(7.43)条件下Cd(Ⅱ)与HSA或BSA的结合平衡.通过非线性最小二乘法拟合Bjerrum方程,首次报道了Cd(Ⅱ)-HSA和Cd(Ⅱ)-BSA体系的逐级稳定常数值,其K_1～K_3的数量级均为10~4;Hill系数和自由能偶合定量分析表明Cd(Ⅱ)与HSA或BSA的结合均产生在类似体系中少见的强的正协同效应,且Cd(Ⅱ)与HSA结合产生的正协同效应大于BSA;Scatchard图分析表明,Cd(Ⅱ)在HSA和BSA中均有3个强结合部位.通过Cd(Ⅱ)与Cu(Ⅱ),Zn(Ⅱ)或Ca(Ⅱ)等竞争结合HSA或BSA的结果,进一步讨论了Cd(Ⅱ)在HSA或BSA中强结合部位的可能位置和(或)配体.     

La（III）与HSA或BSA的结合平衡研究

用平衡透析法详细研究了pH=6.3条件十La(III)与HSA或BSA的结合平衡,Scatchard图分析表明,La(III)在HSA中有2个强结合部位和8个弱结合部位,在BSA中有2个强结合部位和6个弱结合部位,从La(III)与Cu(II),Zn(II)和Cd(II)等的竞争结合HSA或BSA的结果推测,La(III)在HSA或BSA中的一个强结合部位的配位原子可能全部是氧原子,通过非线性最小二乘法拟合Bjerum方程,首次报道了La(III)-HSA和La(III)-BSA体系的逐级稳定常数值,其K1的数量极为10^4,Hill系数及自由能偶合分析表明La(II)与HSA或BSA的结合产生一定的负协同效应。     

La(Ⅲ)与HSA或BSA的结合平衡研究

用平衡透析法详细研究了pH=6.3条件下La(Ⅲ)与HSA或BSA的结合平衡.Scatchard图分析表明,La(Ⅲ)在HSA中有2个强结合部位和8个弱结合部位;在BSA中有2个强结合部位和6个弱结合部位.从La(Ⅲ)与Cu(Ⅱ),Zn(Ⅱ)和Cd(Ⅱ)等的竞争结合HSA或BSA的结果推测:La(Ⅲ)在HSA或BSA中的一个强结合部位的配位原子可能全部是氧原子.通过非线性最小二乘法拟合Bjerrum方程,首次报道了La(Ⅲ)-HSA和La(Ⅲ)-BSA体系的逐级稳定常数值,其K₁的数量级为10⁴.Hill系数及自由能偶合分析表明La(Ⅲ)与HSA或BSA的结合均产生一定的负协同效应.     

Ni(Ⅱ)与HSA或BSA的结合平衡研究

用平衡透析法研究了生理pH(7.43)及pH(5.0)条件下Ni(Ⅱ)与HSA或BSA的结合平衡。Scatchard图分析表明 ,生理pH条件下 ,Ni(Ⅱ)在HSA或BSA中均有2个强结合部位 ,而在pH(5.0)条件下 ,只有1个强结合部位。Hill图分析表明Ni(Ⅱ)与HSA或BSA的结合均产生较强的正协同效应。通过不同pH对Ni(Ⅱ)与HSA或BSA结合的影响及Ni(Ⅱ)与Cu(Ⅱ)和Ca(Ⅱ)的竞争结合的结果 ,推测了两个强结合部位可能的结合位点和配位原子。竞争结果还表明Cu(Ⅱ)对Ni(Ⅱ)的结合有明显拮抗作用。Ca(Ⅱ)对Ni(Ⅱ)的结合影响很小。     

紫外光谱、荧光光谱及平衡透析研究磷钨杂多酸与HSA或BSA的结合平衡

采用紫外光谱法、荧光光谱法并结合平衡透析法研究了磷钨杂多酸(H₇[P(W₂O₇)₆]·xH₂O)与人血清白蛋白(human serum albumin, HSA)或牛血清白蛋白(bovine serum albumin, BSA)的结合平衡. 观测到在生理pH 7.43条件下磷钨杂多酸使HSA和BSA的紫外吸收峰增强, 并使HSA和BSA的特征荧光峰猝灭. Scatchard图分析表明, 磷钨酸在HSA和BSA中均有一个强结合部位. 通过非线性最小二乘法拟合Bjerrum方程, 得出磷钨酸-HSA和磷钨酸-BSA体系的逐级稳定常数.     

镉(Ⅱ)与牛血清白蛋白的相互作用及pH、钙(Ⅱ)、锌(Ⅱ)和表面活性剂的影响

本文用恢复电位法、荧光分光光度法及粘度法研究了镉(Ⅱ)与牛血清白蛋白(BSA)的配位平衡和pH的影响。结果表明BSA有两类镉结合部位(2个强结合和10个弱结合部位)。Cd—BSA配位反应受pH影响,在近中性pH范围Cd(Ⅱ)与BSA结合未接近饱和时,以CURFIT程序对结合曲线拟合发现,每摩尔BSA平均结合Cd(Ⅱ)摩尔数的对数值与游离镉浓度的对数间成线性关系,进一步用Marguardt法处理得到Cd(Ⅱ)与BSA结合平衡方程式:N =K[Cd²⁺]^m,K和m均为pH函数。构象研究表明H⁺和Cd(Ⅱ)的结合都能引起BSA构象改变。用凝胶色谱法测定了Zn(Ⅱ)、Ca(Ⅱ)、吐温—80和十二烷基硫酸钠(SDS)对Cd—BSA结合的影响。Z_n(Ⅱ)可以竞争Cd(Ⅱ)在BSA上结合部位使Cd(Ⅱ)活动化。SDS能够有效抑制Cd(Ⅱ)与BSA结合,这种作用可能与SDS引起BSA构象改变有关。     

Mn(II)与HSA或BSA的结合平衡研究

作者[1] 曾在紫外区观察 LMCT谱带 ,研究了 1∶ 1Mn( ) - HSA和 Mn( ) - BSA在生理 p H(7.43)下金属中心的结构 ,认为 Mn( )在人血清白蛋白 (Human Serum Albumin,简称 HSA)和牛血清白蛋白 (Bovine Serum Albumin,简称 BSA)中的优先结合部位最可能位于 HSA或 BSA的N-端三肽段上 ,涉及 4个含氮基团 ,第 5个配位原子是 ASP1上的羧基氧。用平衡透析法进一步研究了生理 p H条件下 Mn( )在 HSA和 BSA中的结合部位的类型、数目及结合能力 ,并探讨了优先结合部位的可能位置和 (或 )配体。实验同文献 [2 ]。1　Mn( )在 HSA或 B…     

Mn(Ⅱ)与HSA或BSz的结合平衡研究

作者[1]曾在紫外区观察LMCT谱带,研究了1∶1Mn(Ⅱ)-HSA和Mn(Ⅱ)-BSA在生理pH(7.43)下金属中心的结构,认为Mn(Ⅱ)在人血清白蛋白(Human Serum Albumin,简称HSA)和牛血清白蛋白(Bovine Serum Albumin,简称BSA)中的优先结合部位最可能位于HSA或BSA的N-端三肽段上,涉及4个含氮基团,第5个配位原子是ASP1上的羧基氧.用平衡透析法进一步研究了生理pH条件下Mn(Ⅱ)在HSA和BSA中的结合部位的类型、数目及结合能力,并探讨了优先结合部位的可能位置和(或)配体.......     

金属-血清白蛋白的平衡透析——Ⅱ.Ni(Ⅱ)-血清白蛋白体系的别构效应

详细研究了Ni～(2+)离子结合于人血清白蛋白(human serum albumin,HSA)和牛血清白蛋白(bovine serum albumin,BSA)的平衡透析.Ni(II)-HSA和 Ni(II)-BSA体系都得到可以划分成两组的8个结合位置,这2个体系都存在2个优先的结合位置,结合于这 2个位置的 Ni～(2+)离子可以看作是别构效应的效应子,诱导的别构效应符合Monod等人建议的模型.别构参数表明,R-态结合Ni～(2+)离子的能力约为T-态的100倍,HSA的构象显著紧于BSA的.     

Cu(II), Fe(III)与人血清白蛋白相互作用的荧光光谱研究

通过研究Cu(II),Fe(III)对人血清白蛋白(HSA)内源荧光的猝灭,探讨了Cu(II),Fe(III)与人血清白蛋白的结合机理。基于Forster非辐射能量转移机理。获得了人血清白蛋白第一类Cu(II)结合部位与214位色氨酸残基间的距离为1.8nm,并讨论了Cu(II),Fe(III)与HSA结合的差异。     

Binding equilibrium study between Mn( Ⅱ ) and HSA or BSA

The binding of Mn( Ⅱ ) to human serum albumin (HSA) or bovine serum albumin (BSA) has been studied by equilibrium dialysis at physiological pH (7. 43). The Scatchard analysis indicates that there are 1.8 and 1.9 strong binding sites of Mn( Ⅱ ) in HSA and BSA, respectively. The successive stability constants which are reported for the first time are obtained by non-linear least-squares methods fitting Bjerrum formula. For both Mn( Ⅱ )-HSA and Mn( Ⅱ )-BSA systems, the order of magnitude of K1 was found to be 104. The analyses of Hill plots and free energy coupling show that the positive cooperative effect was found in both Mn( Ⅱ )-HSA and Mn( Ⅱ )-BSA systems . The results of Mn ( Ⅱ ) competing with Cu ( Ⅱ ) 、 Zn(Ⅱ)、Cd( Ⅱ) or Ca( Ⅱ ) to bind to HSA or BSA further support the conjecture that there are two strong binding sites of Mn( Ⅱ) in both HSA and BSA. One is most probably located at the tripeptide segment of N- terminal sequence of HSA and BSA molecules involving four groups composed of n     

Equilibrium dialysis of metal-serum albumin (II) Allosteric effect in Ni(II)-serum albumin systems

Detailed studies were carried out on equilibrium dialysis of the binding of Ni²⁺ ion to human serum albumin (HSA) and bovine serum albumin (BSA). The successive stability constants were obtained by the leastsquares fitting. The eight binding sites found for both Ni(II)-HSA and Ni(II)-BSA systems can be divided into two different sets; and for both systems, there exist two identical prior binding sites where the bound Ni²⁺ ions can be considered as allosteric effectors, which induce the allosteric effect in accordance with the model proposed by Monodet al. As indicated by allosteric parameters, the ability of R-state to bind Ni²⁺ ionions is ca. 100 times as much as that of T-state, and the conformation of HSA is markedly tenser than that of BSA. Project supported by the National Natural Science Foundation of China.     

Binding Equilibrium Studies Between Co2+ and HAS or BSA

Introduction Up to now,the interactions of Cu2+,Ni2+ and Zn2+ with serum albumin have been extensively studied[1-3].However,the interaction of serum with Co2+ has rarely been studied.Our study of Co2+-HSA by means of charge transfer spectra indicated that the metal center took an octahedron configuration and the binding site was probably located at the tripeptide segment of the N-terminal of albumin[4].Sadler et al.[5]has reported that the binding site of Co2+ in HSA is located at the tripeptide segment of HSA involving the four nitrogen atoms and a carboxyl oxygen atom of Aspl.In this paper the interaction of HSA and BSA with Co2+ at physiological pH is further studied by equilibrium dialysis.The number of binding sites and the cooperation among the binding sites are reported.According to the equilibrium dialysis results and the study of competition between Co2+ and Cu2+,Ca2+ or Zn2+ to be bound to HSA or BSA,it is suggested that there are three strong binding sites in both HSA and BSA.The possible locations of the strong binding sites of Co2+ in HSA and BSA have also been determined.     

Binding equilibrium study of phosphotungstic acid and HSA or BSA with UV spectrum, fluorescence spectrum and equilibrium dialysis

The binding equilibrium between phosphotungstic acid (H7[P(W2O7)6] · XH2O;PTA) and human serum albumin (HSA) or bovine serum albumin (BSA) has been studied by UV-Vis, fluorescence spectroscopies and equilibrium dialysis. It has been observed that UV absorption enhanced and the fluorescence quenched as the PTA binding to HSA or BSA at physiological pH 7.43(?.02). The Scatchard analysis indicated that there exists a strong binding site of PTA in both HSA and BSA, and the successive stability constants of these two systems are obtained by nonlinear least-squares methods fitting Bjerrum formula.     

Bromocresol green as a new spectrophotometric probe for serum albumins

Bromocresol green (BCG) has been employed as a new spectrophotometric probe to characterise the binding regions of human serum albumin (HSA) and bovine serum albumin (BSA). BCG binds with greater affinity onto BSA than onto HSA. Based on the abilities of ligands Naproxen and l-anilino-8-naphthalenesulphonic acid (ANS) to displace BCG from the serum albumins by competitive or non-competitive mechanism, binding regions were identified for these ligands. It has been found that both Naproxen and ANS share common binding sites with BCG in HSA with the relative ability of Naproxen > ANS on binding to HSA. In the case of BSA, ANS competes with BCG for the same binding sites, whereas Naproxen exhibits non-competitive binding. The highaffinity sites of Naproxen coincide with BCG binding sites while the low-affinity sites occur at sites distinct from the BCG binding region.     

1H and (113)Cd NMR Investigations of Cd(2+) and Zn(2+) Binding Sites on Serum Albumin: Competition with Ca(2+), Ni(2+), Cu(2+), and Zn(2+)

1H and (113)Cd NMR studies are used to investigate the Cd(2+) binding sites on serum albumin (67 kDa) in competition with other metal ions. A wide range of mammalian serum albumins possess two similar strong Cd(2+) binding sites (site A 113-124 ppm; site B 24-28 ppm). The two strong sites are shown not to involve the free thiol at Cys34. Ca(2+) influences the binding of Cd(2+) to isolated human albumin, and similar effects due to endogenous Ca(2+) are observed for intact human blood serum. (1)H NMR studies show that the same two His residues of human serum albumin are perturbed by Zn(2+) and Cd(2+) binding alike. Zn(2+) displaces Cd(2+) from site A which leads to Cd(2+) occupation of a third site (C, 45 ppm). The N-terminus of HSA is not the locus of the two strong Cd(2+) binding sites, in contrast to Cu(2+) and Ni(2+). After saturation of the N-terminal binding site, Cu(2+) or Ni(2+) also displaces Cd(2+) from site A to site C. The effect of pH on Cd(2+) binding is described. A common Cd(2+)/Zn(2+) binding site (site A) involving interdomain His residues is discussed.     

芘与人血清白蛋白和牛血清白蛋白结合位点微环境极性的差异

利用芘(Pyr)的微环境极性探针性质, 采用稳态荧光光谱、 荧光共振能量转移技术结合分子对接法, 对比分析了Pyr分别与人血清白蛋白(HSA)和牛血清白蛋白(BSA)作用机制的差异. 结果表明, HSA和BSA中Pyr的I₁/I₃平均值分别为1.36和0.92; Pyr与HSA和BSA的结合常数分别为1.86×10⁷和1.71×10⁵ L/mol; Pyr与HSA和BSA中色氨酸残基表观距离分别为2.37和2.34 nm. Pyr在HSA和BSA中不同的结合位点位于ⅠB子域和ⅠA子域, 其结合位点周围氨基酸残基的极性是影响Pyr I₁/I₃值的主要原因之一. 实验证实Pyr与HSA和BSA结合作用位点处的微环境极性存在差异.     

光谱法研究噻菁染料与血清蛋白的相互作用

本文通过吸收和荧光光谱法研究了一种噻菁染料与人血清蛋白及牛血清蛋白的相互作用。吸收光谱数据表明,与血清蛋白结合后,噻菁染料单体的吸收峰发生红移,同时强度也有很大变化;还通过吸收光谱计算确定了噻菁染料与血清蛋白的结合位点数（ n ）。与人血清蛋白或牛血清蛋白结合后,噻菁染料的荧光量子产率增加。分析噻菁染料的荧光强度随溶液中血清蛋白浓度的变化得到了二者反应的表观结合常数（ K _a）和自由能变化（ ΔG ）。根据表观结合常数（ K _a）可以判断,人血清蛋白比牛血清蛋白与噻菁染料的结合更强。