Sulfide Oxidation and Signaling

硫化氢（H2S）是一种具有重要生理效应的信号分子， 是哺乳动物硫代谢的产物，合成速率相对较高。H2s 是由硫网络中的三种酶生物合成的，其中两种是胱硫醚β- 合成酶（CBS）和γ-胱硫醚酶，存在于细胞质转硫作用中， 途径，而第三，巯基丙酮酸硫转移酶，涉及半胱氨酸 猫由于H2S是高毒性的，细胞通过有效的氧化来避免其积聚 位于线粒体中并与产生能量的电子耦合的途径 传送链组成蛋白质包括硫化物-醌氧化还原酶， 过硫化物双加氧酶、罗丹酸酶和亚硫酸盐氧化酶。虽然我们对硫化氢的研究 HL 58784支持生物成因，我们对H2S氧化和信号传导的工作是 由GM 130183支持。越来越清楚的是，生物合成和 H2S的分解代谢途径相互作用并相互调节。因此，硫化物 由HL 58784支持的研究计划于今年到期，将被合并到 正式纳入GM 130183的竞争性更新。在这个补充项目中， 下面的具体目标将致力于阐明的基本机制， CBS在正常和疾病状态下对H2S合成的调节：i）阐明CBS在正常和疾病状态下对H2S合成的稳定调节。 CBS中连接体突变体在典型转硫和非典型转硫中的状态动力学 H2S生成反应，（ii）通过EPR研究血红素环境中的扰动 光谱和电位滴定，（iii）评估突变对 血红素铁依赖性调节CO和NO·与亚铁血红素的结合及对细胞凋亡的影响 硫通量，和（iv）结晶似乎不太倾向于 与野生型CBS相比，拟议研究的影响将是 基本的（即阐明CBS水平的变构调节机制， 途径），医学（即理解疾病失败的生物化学基础- 导致CBS突变），最重要的是，培养一个有前途的URM科学家。

Hydrogen sulfide (H2S), a signaling molecule that elicits profound physiological effects, is a product of mammalian sulfur metabolism and is synthesized at relatively high rates. H2S is biosynthesized by three enzymes in the sulfur network of which two, cystathionine beta- synthase (CBS) and gamma-cystathionase, reside in the cytoplasmic transsulfuration pathway while the third, mercaptopyruvate sulfurtransferase, is involved in cysteine catabolism. Since H2S is highly toxic, cells avoid its build-up by an efficient oxidation pathway that is housed in mitochondria and coupled to the energy-generating electron transfer chain. The constituent proteins include sulfide-quinone oxidoreductase, a persulfide dioxygenase, rhodanese and sulfite oxidase. While our studies on H2S biogenesis are supported by HL58784, our work on H2S oxidation and signaling are supported by GM130183. It is becoming increasing clear that the biosynthetic and catabolic pathways for H2S interact and modulate each other. Therefore, the sulfide research supported by HL58784, scheduled to expire this year, will be folded into and then formally included in the competitive renewal of GM130183. In this supplemental project, the following specific aims will be addressed to elucidate fundamental mechanisms of regulation of H2S synthesis by CBS in normal and disease states: i) elucidate the steady state kinetics of linker mutants in CBS in the canonical transsulfuration and non-canonical H2S-generating reactions, (ii) investigate perturbations in the heme environment by EPR spectroscopy and potentiometric titrations, (iii) assess the impact of the mutations on AdoMet-dependent modulation of CO and NO• binding to ferrous heme and on the cellular flux of sulfur, and (iv) crystallize the linker mutants that appear to be less prone to aggregation compared to wild-type CBS. The impact of the proposed studies will be fundamental (i.e. elucidating mechanims of allosteric regulation at the level of CBS and in the pathway), medical (i.e. understanding the biochemical basis of failure of disease- causing CBS mutations), and most importantly, training a URM scientist of high promise.