Tungsten and Molybdenum Oxotransferases

9419019约翰逊本研究的目的是调查的Mo-蝶呤和W-蝶呤中心的Mo/W的配位环境的结构和功能的多样性和性质的蝶呤组件。 该方法涉及使用三种互补的光谱技术，能够选择性地监测的Mo/W-蝶呤中心的电子，磁性和振动特性，即使在存在额外的顺磁性或发色辅基。 Mo（V）和W（V）形式的基态和激发态电子性质将通过变温磁圆二色性和电子顺磁共振光谱确定。 Mo/W-配体和异色蝶呤伸缩模式的振动频率将通过共振拉曼光谱法使用激发到可见电荷转移带进行研究。 电子和振动分配将基于共振激发配置文件，同位素位移，并适当的钼/钨模型复合物的研究。 光谱研究将集中在五个不同类别的氧代转移酶：肝亚硫酸盐氧化酶，DMSO还原酶从球形红细菌，甲酸脱氢酶从梭菌热醋酸，醛铁氧还蛋白氧化还原酶从超嗜热古菌激烈火球菌和ES-4，甲醛铁氧还蛋白氧化还原酶从超嗜热古菌激烈火球菌和嗜热球菌litoralis。 氧代转移酶催化各种各样的氧插入/去除反应，这些反应在碳、氮和硫的代谢中至关重要。 在环境温度下起作用的嗜温生物（植物、细菌和哺乳动物）中，许多这些反应由具有未知结构的新型异蝶呤活性位点的酶催化。 最近对深海火山口嗜热古菌的研究表明，存在类似的具有钨羊齿活性位点的酶，这些酶似乎是嗜温酶的进化祖先。 本研究的目的是调查的结构和功能的多样性，在钼/钨配位环境和蝶呤组分的性质和性质的钼蝶呤和钨蝶呤氧代转移酶。该方法涉及使用三种互补的光谱技术，能够选择性地监测的电子，磁性和振动特性的dopterin和tungstopterin辅因子。 钼（V）和钨（V）形式的基态和激发态电子性质将通过变温磁性圆二色性和电子顺磁共振光谱来建立。 金属配体和蝶呤伸缩模式的振动频率将通过共振拉曼光谱使用激发到可见的电荷转移带进行研究。 电子和振动分配将基于共振激发配置文件，同位素位移，并适当的钼和钨模型复合物的研究。 这些结果对于理解这类酶的催化机制非常重要，并且可能具有重要的进化和生物技术意义。 ***

9419019 Johnson The objective of this research is to investigate the structural and functional diversity of Mo-pterin and W-pterin centers in terms of Mo/W coordination environment and the nature and properties of the molybdopterin component. The approach involves the use of three complementary spectroscopic techniques that are capable of selectively monitoring the electronic, magnetic and vibrational properties of the Mo/W-pterin centers even in the presence of additional paramagnetic or chromophoric prosthetic groups. Ground and excited state electronic properties for Mo(V) and W(V) forms will be established by variable temperature magnetic circular dichroism and electron paramagnetic resonance spectroscopies. Vibrational frequencies for Mo/W-ligand and molybdopterin stretching modes will be investigated by resonance Raman spectroscopy using excitation into visible charge transfer bands/ Electronic and vibrational assignments will be based on resonance excitation profiles, isotope shifts, and studies of appropriate Mo/W model complexes. Spectroscopic studies will focus on five distinct classes of oxotransferases: hepatic sulfite oxidase, DMSO reductase from Rhodobacter sphaeroides, formate dehydrogenase from Clostridium thermoaceticum, aldehyde ferredoxin oxidoreductases from the hyperthermophilic archaea Pyrococcus furiosus and ES-4, formaldehyde ferredoxin oxidoreductases from the hyperthermophilic archaea Pyrococcus furiosus and Thermococcus litoralis. %%% Oxotransferases catalyze a diverse array of oxygen insertion/removal reactions that are of crucial importance in the metabolism of carbon, nitrogen and sulfur. In mesophilic organisms that function at ambient temperatures (plants, bacteria and mammals), many of these reactions are catalyzed by enzymes with a novel molybdopterin active site of unknown structure. Recent studies of hyperthermorphilic archaea from deep sea volcanic vents have revealed the presence of similar enzymes with tungstopteri n active sites, that appear to be evolutionary ancestors of the mesophilic enzymes. The objective of this research is to investigate the structural and functional diversity of molybdopterin and tungstopterin oxotransferases in terms of molybdenum/tungsten coordination environment and the nature and properties of the pterin component. The approach involves the use of three complementary spectroscopic techniques that are capable of selectively monitoring the electronic, magnetic and vibrational properties of the molybdopterin and tungstopterin cofactors. Ground and excited state electronic properties for molybdenum(V) and tungsten(V) forms will be established by variable temperature magnetic circular dichroism and electron paramagnetic resonance spectroscopies. Vibrational frequencies for metal-ligand and pterin stretching modes will be investigated by resonance Raman spectroscopy using excitation into visible charge transfer bands. Electronic and vibrational assignments will be based on resonance excitation profiles, isotope shifts, and studies of appropriate molybdenum and tungsten model complexes. The results will be important in understanding the catalytic mechanisms of this class of enzymes and are likely to have important evolutionary and biotechnological implications. ***