EPR OF METHEMOGLOBIN FORMATION IN RED CELLS W/ UNSTABLE HEMOGLOBIN

不稳定血红蛋白红细胞中高铁血红蛋白形成的 EPR

• 批准号: 6121166
• 负责人: ODED SHAKA
• 金额: $ 2.73万
• 依托单位: ALBERT EINSTEIN COLLEGE OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-05-05 至 2000-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6121166
• 关键词: bioengineering /biomedical engineering; biological products; biomaterials; biomedical equipment development; biomedical resource; technology /technique

A Hb from the chloroplast of Chlamydomonas eugametos has been cloned andexpressed in E. coli. This Hb resembles several invetebrate in having a tyr residue in the B10 and a glut in the E7 positions, both of which are believed to participate in H-bonding to bound O2 that results in extremely slow off-rates. On the other hand, Chlamydomonas Hb is unusual in that the ferrous protein has a high-spin to low spin (six-coordinate) transition pK of 8.5, whereas the ferric protein has a high-spin to low spin (six-coordinate) transition pK of 6.4. This suggests that the distal ligand of the low spin forms of the ferrous and the ferric proteins may be different. The ferric protein exhibits a single low spin form with g values of 2.52, 2.31, 1.86, and thus an anisotropy similar to that of myoglobin hydroxide. However, 17O EPR and 18O resonance Raman studies failed to provide direct evidence for a hydroxide ligand. Spectroscopic studies on the distal mutants of the B10 Tyr, E7 Gln, and the E10 Lys residues have so far failed to identify a possible amino acid ligand. Further studies are being conducted to identify the distal ligand and to understand the unusual low spin EPR spectrum.

来自真配衣藻 (Chlamydomonas eugametos) 叶绿体的 Hb 在大肠杆菌中克隆并表达。 该 Hb 类似于几种无脊椎动物 在 B10 位置有 tyr 残基，在 E7 位置有 glut， 据信两者都参与氢键结合 O2 这导致解离速度极慢。 另一方面， 衣藻 Hb 的不同寻常之处在于，亚铁蛋白具有 高自旋到低自旋（六坐标）跃迁 pK 为 8.5，而 铁蛋白具有高自旋到低自旋（六坐标） 转变 pK 为 6.4。 这表明低的远端配体 亚铁蛋白和三价铁蛋白的自旋形式可能不同。 铁蛋白表现出单一的低自旋形式，g值为 2.52、2.31、1.86，因此具有与肌红蛋白相似的各向异性 氢氧化物。 然而 17O EPR 和 18O 共振拉曼研究未能 为氢氧根配体提供直接证据。 光谱研究 B10 Tyr、E7 Gln 和 E10 Lys 残基的远端突变体 迄今为止未能鉴定出可能的氨基酸配体。 更远 正在进行研究以确定远端配体并 了解不寻常的低自旋 EPR 谱。