Transsulfuration and Hyperhomocysteinemia

转硫和高同型半胱氨酸血症

• 批准号: 7896574
• 负责人: RUMA V BANERJEE
• 金额: $ 33.63万
• 依托单位: UNIVERSITY OF MICHIGAN AT ANN ARBOR
• 依托单位国家: 美国
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-08-01 至 2012-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7896574
• 关键词: Address; Allosteric Regulation; Alzheimer' s Disease; Amino Acids; Ammonia; Animal Model; Antioxidants; Arterial Occlusive Diseases; Behavior; Binding Proteins; Biochemical; Biogenesis; Biological; C-terminal; Cardiovascular Diseases; Catalytic Domain; Cell Nucleus; Cells; Clinical; Collaborations; Cystathionine; Cysteine; Data; Enzymes; Functional disorder; Gap Junctions; Generations; Genes; Glutathione; Goals; Heme; Homocysteine; Homocystine; Human; Hydrogen; Hydrogen Sulfide; Hyperhomocysteinemia; In Vitro; Individual; Inherited; Kinetics; Laboratories; Lead; Length; Lyase; Mammals; Mass Spectrum Analysis; Mediating; Metabolic; Metabolism; Methionine; Methionine Metabolism Pathway; Methods; Methylation; Modeling; Motion; Mutagenesis; Mutation; Neural Tube Defects; Neurodegenerative Disorders; Neuromodulator; Nuclear; Nutrient; Oxidation-Reduction; Parkinson Disease; Pathway interactions; Patients; Peptide Mapping; Physical condensation; Physiological; Production; Pyridoxal Phosphate; Reagent; Regulation; Research Personnel; Risk Factors; Role; Serine; Source; Spectrum Analysis; Structure; Sulfhydryl Compounds; Sulfur Metabolism Pathway; Testing; Thiol Disulfide Oxidoreductase; Variant; Yeasts; base; cofactor; enzyme pathway; in vivo; insight; interest; mathematical model; meetings; mutant; residence; yeast two hybrid system

DESCRIPTION (provided by applicant): The transsulfuration pathway is important for the intracellular disposal of homocysteine, an intermediate in methionine metabolism. Elevated levels of homocysteine constitute a risk factor for cardiovascular diseases, certain neurodegenerative diseases (viz. Alzheimer's disease and Parkinson's disease) and neural tube defects. Two successive PLP-dependent enzymes in the transsulfuration pathway, cystathionine ?- synthase (CBS) and cystathionine-? lyase (CGL), convert homocysteine to cysteine, the limiting reagent in the synthesis of glutathione, the cell's major antioxidant. Mutations in CBS are the single most common cause of hereditary hyperhomocysteinemia and over 130 mutations in this gene have been described in patients. CBS catalyzes the condensation of serine and homocysteine to generate cystathione and is regulated by heme, sumoylation and the allosteric activator, S-adenosylmethionine. CGL catalyzes the elimination of cystathionine to cysteine, ?-ketoglutarate and ammonia. Mutations in this enzyme lead to cystathionuria and are sometimes correlated with hyperhomocysteinemia. CBS and CGL are believed to be important in the biogenesis of H2S, a neuromodulator and a vasorelaxant, but the physiological relevance of their H2S generation capacity is unknown. Additionally, significant gaps exist in our understanding of the regulation of CBS which modulates its role in intracellular clearance of homocysteine. Our goals are (i) to elucidate the mechanistic basis of redox- and CO-induced sensitivity of the enzyme mediated by the heme cofactor and to define the role of thiol-disulfide oxidoreductase in regulation, (ii) to determine the effect of CBS sumoylation on activity and allosteric regulation and the significance of CBS's nuclear localization (iii) to elucidate the biochemical penalties associated with select pathogenic mutations in the heme, catalytic and C-terminal regulatory domains and (iv) to determine the mechanism and regulation of CGL in addition to the kinetics for H2S generation and to employ a mathematical model of methionine metabolism to evaluate the contribution of the transsulfuration pathway to H2S production at physiologically relevant concentrations of reactants. These studies will provide important insights into the function and regulation of clinically important human enzymes in the transsulfuration pathway that control intracellular levels of homocysteine, modulate glutathionine-based redox homeostatis and possibly, represent the source of H2S biogenesis.

描述（由申请人提供）：转硫途径对于同型半胱氨酸的细胞内处置非常重要，蛋氨酸代谢中的中间体。同型半胱氨酸水平升高构成心血管疾病，某些神经退行性疾病（即阿尔茨海默氏病和帕金森氏病）和神经管缺陷的危险因素。在转硫途径中的两个连续的PLP依赖性酶，胱硫硫氨酸？ - 合酶（CBS）和胱胱氨而在硫代氨酸中？裂解酶（CGL），将同型半胱氨酸转换为半胱氨酸，半胱氨酸是谷胱甘肽的合成中的极限试剂，谷胱甘肽是细胞的主要抗氧化剂。 CBS中的突变是遗传性高脑结构血症的最常见原因，该基因中已经描述了该基因中的130多个突变。 CBS催化丝氨酸和同型半胱氨酸的凝结以产生囊肿，并由血红素，sumoylation和变构激活剂S-腺苷甲硫氨酸调节。 CGL催化消除半胱氨酸的半胱氨酸，？酮戊二酸和氨。该酶的突变导致膀胱硫硫脲，有时与高脑结膜血症相关。 CBS和CGL被认为在H2S的生物发生，神经调节剂和血管舒张中很重要，但是其H2S生成能力的生理相关性尚不清楚。另外，我们对CBS调节的理解中存在着显着的差距，该障碍调节其在同型半胱氨酸的细胞内清除率中的作用。我们的目标是（i）阐明由血红素辅助因子介导的氧化还原和共同诱导的敏感性的机理基础，并定义了硫醇 - 硫化物氧化还原酶在调节中的作用，（ii）确定CBS Sumoylation对活动和bot susporiatient and Sumperiatient and sulosteric Condientiatient and Boiie cbs to II III的效果（II）的作用（II）。血红素，催化和C末端调节结构域的致病突变以及（iv）确定CGL的机制和调节，除了H2S生成的动力学外，并采用甲硫氨酸代谢的数学模型来评估在物理学浓度的H2S生产型H2S生产的贡献。这些研究将提供对临床上重要人类酶在转化途径中的功能和调节的重要见解，该酶控制了同型半胱氨酸的细胞内水平，调节基于谷胱甘肽的氧化还原稳态，可能代表了H2S生物发生的来源。