Mechanism for the increase in solubility of deoxyhemoglobin S due to cross-linking the beta chains between lysine-82 beta 1 and lysine-82 beta 2.
Mechanism for the increase in solubility of deoxyhemoglobin S due to cross-linking the beta chains between lysine-82 beta 1 and lysine-82 beta 2.
复制标题
由于赖氨酸 82 β 1 和赖氨酸 82 β 2 之间的 β 链交联而增加脱氧血红蛋白 S 溶解度的机制。
DOI：
10.1021/bi00266a027
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发表时间：
1982
期刊：
影响因子：
2.9
通讯作者：
Walder,JA
中科院分区：
文献类型：
--
作者：
Chatterjee,R;Walder,RY;Arnone,A;Walder,JA
Ranjit Chatterjee, Roxanne Y. Walder, Arthur Arnone, and Joseph a . Walder* ' 1摘要：在先前的出版物[Walder， J. a . a ., Walder， R. Y., & Arnone, a .(1980) J. Mol. Biol. 141, 195-216]中，我们发现他（3,5 -二溴水杨基）富马酸酯在2,3 -二磷酸甘油酸结合位点选择性地与氧化血红蛋白反应，以交联Lys-82/3[和Lys-82/32]之间的四聚体/3链。这种化学修饰显著增加脱氧血红蛋白S的溶解度，因此在镰状细胞病的治疗中具有潜在的临床价值。通过对脱氧形式交联衍生物的晶体学分析，我们发现这种修饰导致Lys-82/3和邻近的/3链残基（特别是在脱氧血红蛋白S纤维中形成val6受体位点的ph -85/3和Leu-88/3）被拉向四聚体的中心腔。在血红蛋白S突变位点区域，残差6/3未见结构改变。这些结果表明，受体位点的扰动程度与两个赖氨酸残基交联导致脱氧血红蛋白S溶解度的增加之间存在直接关系。为了验证这一假设，我们比较了他（3,5 -二溴水杨基）琥珀酸酯（C4）、他（3,5 -二溴水杨基）戊二酸酯（C5）和他（3,5 -二溴水杨基）己二酸酯（C6）交联的脱氧血红蛋白A的结构和相应的脱氧血红蛋白s衍生物的溶解度。随着桥接基团长度的增加，Lys-82/3向中心腔的运动逐渐减少，并伴随Val-6受体位点的扰动。相应的，c4交联衍生物的溶解度增加最多（接近50%），并且随着交联长度的增加，溶解度降低，接近天然脱氧血红蛋白s的溶解度。为了完成反应途径的立体化学分析，我们以CO-/34作为正常配体a2/32四聚血红蛋白模型，确定了交联对配体季态结构的影响。这些研究的结果表明，富马酰基能够跨越氧血红蛋白中的两个赖氨酸残基，而不会扰乱蛋白质的结构。在这项工作中得到的结构相关性为设计新的抗镰刀状化合物提供了重要的约束。镰状细胞病的分子基础是血红蛋白分子内的单点突变；谷氨酸在/3链的第6位被缬氨酸取代。这种突变对血红蛋白的功能特性影响相对较小，但会显著降低其脱氧形式的溶解度（Perutz et al., 1951）。在生理条件下，脱氧血红蛋白S最初以延长的螺旋纤维的形式从溶液中析出。在红细胞内，这些纤维倾向于彼此平行排列，形成大的聚集体，扭曲细胞的形态，产生各种异常形状，最典型的是镰状。与正常红细胞相比，这些形状异常的细胞不易变形，是导致血管闭塞并发症的原因。对镰状细胞病发病机制的了解促使人们努力设计能够通过共价干扰脱氧血红蛋白S聚合的试剂
Ranjit Chatterjee, Roxanne Y. Walder, Arthur Arnone, and Joseph A. Walder*’1 abstract: In a previous publication [Walder, J. A., Walder, R. Y., & Arnone, A.(1980) J. Mol. Biol. 141, 195-216], we showed that bis (3, 5-dibromosalicyl) fumarate reacts selectively with oxyhemoglobinat the 2, 3-diphosphoglycerate binding site to cross-link the/3 chains of the tetramer between Lys-82/3 [and Lys-82/32. This chemical modification markedly increases the solubility of deoxyhemoglobin S and is therefore of po-tential clinical value in the management of sickle cell disease. By crystallographic analysis of the cross-linked derivative in the deoxy form, we showed that this modification causes Lys-82/3 and the neighboring/3-chain residues (specifically Phe-85/3 and Leu-88/3 which form the acceptor site for Val-6 within the deoxyhemoglobin S fiber) to be pulledinward to-ward the central cavity of the tetramer. No alterations in the structure were observed in the region of the mutation site in hemoglobin S, residue 6/3. These results suggested that there is a direct relationship between the magnitude of the perturbation of the acceptor site and the increase in the solubility of deoxyhemoglobin S which results from cross-linking the two lysine residues. To test this hypothesis, we have compared the structures of deoxyhemoglobin A cross-linked by bis (3, 5-di-bromosalicyl) succinate (C4), bis (3, 5-dibromosalicyl) glutarate (C5), and bis (3, 5-dibromosalicyl) adipate (C6) and the solu-bilities of the corresponding derivatives of deoxyhemoglobin S. As the length of the bridging group is increased, there is a progressive decrease in the movement of Lys-82/3 toward the central cavity and in the accompanying perturbation of the acceptor site for Val-6. Correspondingly, the solubility of the C4-cross-linked derivative is increasedby the largest amount (nearly 50%), and as the cross-link is increased in length, the solubility decreases, approaching that of native deoxyhemoglobin S. To complete the analysis of the stereochemistry of the reaction pathway, we have determined the effect of the cross-link on the structure in the liganded quaternary state by using CO-/34 as a model of normal liganded a2/32 tetrameric hemoglobins. The results of these studies indicate that the fumaryl group is able to span the two lysine residues in oxy-hemoglobin without perturbing thestructure of the protein. The structural correlations arrived at in this work provide important constraints for the design of new antisickling com-pounds. e molecular basis for sickle cell disease is a single point mutation within the hemoglobin molecule; glutamic acid at the sixth position of the/3 chains is replaced by valine. This mutation has relatively little effect on the functional properties of hemoglobin but does markedly reduce its solubility in the deoxy form (Perutz et al., 1951). Under physiological con-ditions, deoxyhemoglobin S initially precipitates from solution in the form of extended helical fibers. Within the erythrocyte, these fibers tend to align parallel to one another to form large aggregates which distort the morphology of the cell, giving rise to a variety of abnormal shapes, most characteristically the sickled form. These abnormally shaped cells are less deformable than the normal erythrocyte and are responsible for thevaso-occlusive complications of the disease. Knowledge of the pathogenesis of sickle cell disease has led to manyefforts to design reagents that would interfere with the polymerization of deoxyhemoglobin S either by covalently