Modulation of the Heme Pocket Conformation or Dual Concerted Mechanism upon Substitution of Hydrogen Sulfide by Oxygen Binding to an Unusual Hemoglobin?

Lopez-GarrigaMCB-9974961本研究的目的是研究从Lucina pectinata分离的血红蛋白（HbI）的氧化还原、配体选择和配体稳定过程的分子基础。 这种血红蛋白可能是唯一的血红素蛋白，执行其功能，运输H2S的细菌共生体，在硫化氢结合铁的状态。 假定血红素-Fe +3 SH 2部分和Gln（E7）基团之间存在H-键合以稳定HbISH 2中心。 同样，其他氨基，特别是Gln（E7）、Phe（B10）和Phe（E11）可以与其他HbI配体CO和O2相互作用。 为了了解这种酶的结构和功能特性，定点突变的HbI将被用来确定其关联和解离常数与不同的配体作为pH值的函数。这些研究结合FTIR和共振拉曼工作应该产生新的见解有关的因素，控制H2S结合，运输和交付。本研究的目的是研究血红素蛋白的配体亲和力差异。 目前，还没有确定这些差异是否来自静电效应，从空间约束，或从氢键的差异。 希望这些研究与血红蛋白I从Lucina pectinata将解决这些问题中的一些，并产生新的见解，这种不寻常的血红蛋白的结构和功能特征。 这项工作很可能产生的信息，可能是有用的重组HbI蛋白的设计与商业用途，例如，作为一个特定的H2S生物传感器。 这些蛋白质也可用于从工业或自然过程中去除有毒的H2S，如厌氧发酵，污水和天然气生产。

Lopez-GarrigaMCB-9974961The objective of this research is to investigate the molecular basis for oxidation-reduction, ligand selection, and ligand stabilization processes of hemoglobin (HbI) isolated from Lucina pectinata. This hemoglobin is probably the only heme protein that carries out its function, to transport H2S to a bacteria symbion, in a hydrogen-sulfide bound ferric state. The presence of H-bonding between the heme-Fe+3 SH2 moiety and the Gln(E7) group is postulated to stabilize the HbISH2 center. Likewise, other amino groups, in particular, Gln(E7), Phe(B10), and Phe(E11) may interact with other HbI ligands, CO and O2. In order to understand the structural and functional characteristics of this enzyme, site-directed mutants of HbI will be used to determine its association and dissociation constants with different ligands as a function of pH. These studies in conjunction with the FTIR and resonance Raman work should produce new insight about factors that control H2S binding, transport, and delivery. The goal of this research is to study the ligand affinity differences in heme proteins. At present, it is not established whether these differences arise from electrostatic effects, from steric constraints, or from hydrogen-bonding differences. It is hoped that the these studies with hemoglobin I from Lucina pectinata will resolve some of these issues and produce new insight about the structural and functional characteristics of this unusual hemoglobin. The work is likely to produce information that may be useful in the design of recombinant HbI proteins with commercial uses, for example, as a specific H2S biosensor. These proteins may also be used for the removal of toxic H2S from industrial or natural processes, such as anaerobic fermentation, sewage, and natural gas production.