RAMAN AND TIME-RESOLVED RAMAN STUDIES OF HEME PROTEINS

这个涉及血红素蛋白质的项目的总体长期目标是了解相关多肽与共同的血红素基团相互作用的分子机制，以产生这类蛋白质所特有的显着功能多样性。基本的策略是将强大的光谱探针，如共振拉曼(RR)和时间分辨拉曼(TR3)应用于天然和系统操作的蛋白质，以揭示调节血红素反应性的结构和动态相互作用。由于这些蛋白质参与了大量重要的生理过程，包括氧运输和多种类型的氧化代谢途径，因此识别导致这种广泛不同功能的因素将对了解它们在正常和异常状态下的行为有明显的好处。在这里提出的工作中，最近记录的一种针对天然血红蛋白四聚体的有效策略，利用了分子振动的同位素敏感性，正在被应用于选择位置修饰的血红蛋白。预计将积累的新数据将有助于更好地理解血红蛋白与合作配体结合的分子机制，血红蛋白是一种通常作为重要变构过程的范例的蛋白质。此外，共振拉曼光谱还将用于探索细胞色素P450和哺乳动物过氧化物酶等氧化血红素酶的位点修饰衍生物的活性部位结构，这些蛋白质在许多代谢过程和防御微生物方面都很重要。

The general long-term goal of this program involving heme proteins is to attain an understanding of the molecular mechanisms by which the associated polypeptides interact with a common heme group to produce the remarkable functional diversity which is characteristic of this class of proteins. The essential strategy is to apply powerful spectroscopic probes such as resonance Raman (RR) and time-resolved Raman (TR3) to the native and systematically manipulated proteins in order to reveal the structural and dynamic interactions which regulate heme reactivity. Inasmuch as these proteins are involved in a large number of important physiological processes, including oxygen transport and many types of oxidative metabolic pathways, identification of the factors responsible for this widely varied function would be of obvious benefit for attaining an understanding of their behavior in normal and abnormal states. In the work proposed here an effective strategy recently documented for the native hemoglobin tetramer, which exploits the isotopic sensitivity of molecular vibrations, is being applied to selected site modified hemoglobins. The new data to be accumulated is expected to lead to a better understanding of the molecular mechanism of cooperative ligand binding by hemoglobin, a protein which serves as a paradigm for generally important allosteric processes. In addition, resonance Raman spectroscopy will be used to probe the active site structures of site modified derivatives of oxidative heme enzymes such as cytochromes P450 and mammalian peroxidases, proteins which are important in many metabolic processes and in defense against microorganisms.