【作者】 黄瑾；

【导师】 梁宏；

【作者基本信息】 广西师范大学 ， 无机化学， 2001， 硕士

【摘要】 第一部分：用紫外光谱扫描发现在生理pH(7.43)条件下Co(Ⅱ)与人血清白蛋白(HSA)或牛血清白蛋白(BSA)的结合有明显的滞后效应，表明Co(Ⅱ)与HSA或BSA的结合可能诱导白蛋白发生了构象态的缓慢变化(A-B转化)；测得并讨论了这一构象变化的速度常数和活化参数；推测这一构象变化可能是由Co(Ⅱ)结合在白蛋白的N-端三肽段结合位后牵动白蛋白I_A亚区内相对疏水的谷作了一次“铰链式运动”，进而诱使整个分子的构象逐渐发生了变化，使Co(Ⅱ)的其他结合部位暴露出来，表现为正协同效应。Co(Ⅱ)-HSA和Co(Ⅱ)-BSA体系的LMCT谱带还显示出一种鲜见报道的、具有偶极-偶极跃迁机理的减色效应。 第二部分：用紫外光谱扫描发现等电点pH(5.3)条件下，Fe(Ⅱ)与人血清白蛋白(human serum albumin，简称HSA)或牛血清白蛋白(bovine serum albumin，简称BSA)的结合有明显的滞后效应，表明Fe(Ⅱ)与HSA或BSA的结合可能诱导蛋白质构象发生从对Pe(Ⅱ)有较弱亲和力至较强亲和力缓慢变化(T-R转化)。测得并讨论了这一构象变化的速度常数和活化参数；推测这一构象变化可能是由Fe(Ⅱ)结合在白蛋白后，诱使整个分子的构象逐渐发生了变化，使Fe(Ⅱ)的其他结合部位暴露出来，表现为正协同效应。用平衡透析法首次研究了Fe(Ⅱ)与HSA或BSA的结合平衡。Scatchard图分析表明，Fe(Ⅱ)在HSA或 广酉帅无大攀习士论文：应另白岳白的有关研丑BSA中均有两个强结合部位，通过非线形最小H乘法拟合 Bjerrum方程，得出 Fe（11 yHSA和 Fe（11卜 BSA体系的逐级稳定常数．第三部分：采用紫外光谱法、荧光光谱法并结合平衡透析法首次研究了磷钨杂多酸叮7R仰O7）6卜XHZO）与人血清白蛋白或牛血清白蛋白的结合平衡．观测到在生理咖（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的特征荧先峰淬灭．Seat。hard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历 方程，得出磷钨酸－HSA和磷钨酸－BSA体系的逐级稳定常数．更多还原

【Abstract】 Part IA notable hysteretic effect has been observed in the interaction of Co( II) with human serum albumin (HSA) or bovine serum albumin (BSA) by using UV-Visible spectrometry at physiological pH(7.43), which shows that the binding between Co( II) and HSA or BSA may induce a slow transition of HSA or BSA (A-B transition). And the rate constants and activation parameters of this transition have been measured and discussed. It is inferred that such a conformation transition may occur due to the binding of the first Co( II) ion with the peptide segment of N-terminal residues 1-3, which results in a "hinged movement" of the relatively hydrophobic "valley" in the IA subdomain. This process leads to a slow conformational transition in the albumins, makes the other binding sites of Co( II) exposed, and shows a positive cooperativity effect. The LMCT(ligand to metal charge transition) bands of Co( II )-HSA and Co( II)BSA systems also show a kind of hypochromic effect featuring the dipole-dipole interaction mechanism. This phenomenon israrely report.Part IIA notable hysteretic effect has been observed in the interaction of Fe( II) with human serum albumin (HSA) or bovine serum albumin (BSA) by usln2 UV-Visible spectrometry at the isoelectric point pH(5.3), which shows that the binding between Fe( II) and HSA or BSA may induce a slow conformational transition of HSA or BSA from the conformation of weaker affinity for Fe( II) to the one of stronger affinity (T-R transition). And the rate constants and activation parameters of this transition have been measuredo Project supporte4by the National Science Foundation of China (NO. 299621001),and the Foundation for Talents of the Ten~ Hunred. Thousand in Guangxi.3and discussed. It is inferred that such a conformation transition may occur due to the binding of the first Fe( II) ion with sreum albumin. This process leads to a slow conformational transition in the albumins, makes the other binding sites of Fe( II) exposed, and shows a positive cooperativity effect. The binding equilibrium between Fe( II) and human serum albumin (HSA) or bovine serum albumin (BSA) has been studied by equilibrium dialysis for the first time. The Scatchard analysis indicated that there exist one strong binding site of Fe( II) in both HSA and BSA, and the successive stability constants of Fe( II )-HSA and Fe( II )-BSA systems are obtained by non-linear least-squares methods fitting Bjerrum formula.Part IllThe binding equilibrium between phosphotungstic acid (H7[P(W20,)6] o 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 for the first tune that UV absorption enhanced and the fluorescence quenched as the PTA binding to HSA or BSA at physiological pH (7.43 ± 0.02). The Scatchard analysis indicats that there exist one strong binding site of PTA in both HSA and BSA, and the successive stable constants of these two systems are obtained by non-linear least-squares methods fitting Bjerrum formula.更多还原