BAND 3 N-TERMINAL AA 10-16 AND DEOXY S POLYMERIZATION

带 3 N 端 AA 10-16 和脱氧 S 聚合

• 批准号: 3353259
• 负责人: JOHN W HARRIS
• 金额: $ 9.48万
• 依托单位: CASE WESTERN RESERVE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1988
• 资助国家: 美国
• 起止时间: 1988-02-01 至 1991-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3353259
• 关键词: chemical binding; chemical structure function; conformation; gel electrophoresis; hemoglobin Ss; polymerization; protein sequence; sickle cell anemia; synthetic peptide

The polymerization and sol-gel transformation of deoxyhemoglobin S will be inhibited by an unexplored mechanism in which the close approach of hemoglobin molecules necessary to initiate and propagate polymerization is prevented and the hemoglobin is allowed to remain fully functional. Peptides of the amino acid sequence present in the N-terminal portion of Band 3 of the human erythrocyte bind reversibly to hemoglobin A at the 2,3-DPG receptor locus. Binding to the deoxy conformation is much greater than to the oxy. The peptides extend deep into the cavity between the beta chains and, depending on length, protrude for varying distances beyond the confines of the tetrad. The interactions between fragments of the N-terminal cytoplasmic portion of Band 3 and hemoglobin S are comparable with those of hemoglobin A but the effect of such peptides on the polymerization of deoxy S has not been explored. It is postulated that 1) a 15 amino acid peptide of the same sequences as in the N-terminal cytoplasmic domain of Band 3 will enter the inter-betaS chain region a distance of 18 angstrom and protrude approximately 27 angstrom outside the molecule to occupy and occlude a hemispheric volume of 27 angstrom radius around the 2,3-DPG binding site of the betaS chains and 2) the protruding portion of the peptide will, by sheer bulk or by covering up specific interacting sites, prevent the 1-5 angstrom approaches that the surface beta 6 mutant and other contact areas must make to initiate polymerization. Additional steric impedance to hemoglobin S polymer formation may arise from 1) disordering of the beta chains in the 10-12 residues f the C-termini and in the 3 N-terminal amino acids before the A helix (Changes induced in hemoglobin A by the peptide), and 3) the formation of binary complexes of deoxyhemoglobin S molecules tethered together by the peptide in beta-to-beta chain apposition. These could not properly incorporate into the polymer. The peptides will be designed, synthesized, purified, and characterized: evaluation of reactions with hemoglobin will be by Csat, time-viscosity profile, physical properties of gel, P50, competitive binding with other polyanions, change in charge and M.W. The binding, reversibility, and steric interference will be optimized by varying the molar rations of peptide to hemoglobin, peptide length, amino acid sequence, an contour. Results will provide new data on nucleation, the polymerization reaction, and the structure of polymer and gel. A new class of inhibitors will be defined that may ultimately find applicability in controlling the intracellular polymerization basic to the pathophysiology and clinical manifestations of sickle cell disorders.

脱氧血红蛋白的聚合和溶胶-凝胶转化 S 将被一种未探索的机制所抑制，其中关闭 血红蛋白分子的启动和启动所必需的方法 阻止传播聚合并允许血红蛋白 保持功能齐全。 氨基酸序列的肽 存在于人类带 3 的 N 末端部分 红细胞在 2,3-DPG 受体处可逆地与血红蛋白 A 结合 轨迹。 与脱氧构象的结合远大于与脱氧构象的结合 氧气。 肽延伸至β-肽之间的空腔深处 链条，根据长度突出不同的距离 超出了四分体的范围。 之间的相互作用 带 3 的 N 端细胞质部分的片段和 血红蛋白 S 与血红蛋白 A 相当，但 此类肽对脱氧S聚合的影响尚未 被探索过。 假设 1) 15 个氨基酸的肽 具有与 N 端胞质结构域相同的序列 频段 3 将进入距离为 18 的 betaS 链间区域 埃并向外突出约27埃 分子占据并遮挡 27 埃的半球体积 betaS 链 2,3-DPG 结合位点周围的半径和 2) 肽的突出部分将通过绝对体积或通过 覆盖特定的相互作用位点，防止1-5埃 表面β6突变体和其他接触区域的方法 必须引发聚合。 附加空间阻抗 血红蛋白 S 聚合物形成的原因可能是 1) C 末端 10-12 个残基中的 β 链和 A 螺旋之前的 3 个 N 末端氨基酸（在 血红蛋白A由肽）和3）形成二元 脱氧血红蛋白 S 分子通过 β-β链并置的肽。 这些都不能正确 并入聚合物中。 肽将被设计， 合成、纯化和表征：反应评估 血红蛋白将通过 Csat、时间-粘度曲线、物理 凝胶特性、P50、与其他聚阴离子的竞争性结合、 电荷和分子量的变化 结合力、可逆性和空间位阻 通过改变摩尔比可以优化干扰 肽与血红蛋白、肽长度、氨基酸序列、 轮廓。 结果将提供有关成核的新数据， 聚合反应，以及聚合物和凝胶的结构。 一个 新一类抑制剂将被定义，最终可能会发现 控制细胞内聚合基础的适用性 镰状细胞病的病理生理学和临床表现 失调。