Mechanistic Studies of Lipoic Acid Synthase

硫辛酸合成酶的机理研究

• 批准号: 7582291
• 负责人: SQUIRE J. BOOKER
• 金额: $ 25.2万
• 依托单位: PENNSYLVANIA STATE UNIVERSITY, THE
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-04-01 至 2011-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7582291
• 关键词: 3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide); 5' -deoxyadenosine; 9-mercaptodethiobiotin; Abbreviations; Acids; Active Sites; Acyl Carrier Protein; Acylation; Address; Amino Acid Substitution; Amino Acids; Anabolism; Antioxidants; Binding; Biochemistry; Biotin; Carbon; Carrier Proteins; Cell physiology; Cells; Cessation of life; Chemicals; Cleaved cell; Commit; Competence; Complex; Cysteine; Data; Detection; Distal; Electron Nuclear Double Resonance; Electrons; Energy Metabolism; Enzymes; Escherichia coli; Feedback; Flavodoxin; Fourier transform ion cyclotron resonance; Goals; Housing; Hydrogen; Hydrogen Bonding; In Vitro; Kinetics; Label; Left; Lysine; Mammalian Cell; Mass Spectrum Analysis; Methionine; Methods; Molecular; Monitor; Multienzyme Complexes; Mycobacterium tuberculosis; Non-Insulin-Dependent Diabetes Mellitus; Octanoic Acids; Pathway interactions; Patients; Positioning Attribute; Post-Translational Protein Processing; Production; Proteins; Pyridoxal Phosphate; Pyruvate Dehydrogenase Complex; Reaction; Reducing Agents; Regulation; Research; Roentgen Rays; Role; S-Adenosylmethionine; Site; Source; Spectrum Analysis; Structure; Sulfur; Sum; Testing; Textbooks; Thioctic Acid; Time; Transferase; Tuberculosis; Work; absorption; abstracting; acyl group; amino group; analog; bacterial genetics; base; biotin synthase; carboxylate; cofactor; design; desthiobiotin; dihydrolipoamide dehydrogenase; feeding; flavodoxin NADPH oxidoreductase; glucose metabolism; in vivo; inhibitor/antagonist; interest; lipoamidase; lipoate-protein ligase; lipoic acid synthase; member; molecular mass; mutant; polypeptide; small molecule; stoichiometry

DESCRIPTION (provided by applicant): Lipoic acid is an essential sulfur-containing cofacor that is found in several multienzyme complexes that are involved in energy metabolism. In its functional form it is covaleritly attached to the epsilon amino group of a specific lysine residue on a designated lipoyl carrying protein. The detailed manner in which it functions in these complexes has been known for quite some time, and is found in almost every beginning biochemistry textbook. By contrast, only within the last few years has a clear understanding of its biosynthesis begun to emerge. Lipoic acid is biosynthesized in its cofactor form rather than its free acid form, requiring two proteins that are dedicated to the transformation. The first, octanoyl transferase (LipB) catalyzes the transfer of the eight-carbon fatty acyl chain from octanoyl-ACP to one of the several lipoyl carrying proteins in the cell. The second protein, lipoyl synthase (LipA) catalyzes the insertion of two sulfur atoms at positions 6 and 8 of the fatty acyl group, affording the lipoyl cofactor. LipA is a member of radical SAM superfamily of enzymes, which use a [4Fe-4S] and S-adenosylmethionine to generate high-energy radicals that are intermediates in each reaction. The long-term objective of this proposal is to understand at the detailed molecular level how each of these enzymes work. Particular focus will be directed at LipA, to understand exactly from where the sulfur atom that is inserted into the substrate is derived. Efforts will involve bacterial genetics, transient state kinetics, and spectroscopy (UV-vis, EPR, M"ssbauer, ENDOR, and FT-ICR mass spectrometry). Aside from the involvement of lipoic acid as a cofactor in enzyme complexes of energy metabolism it is known to modulate glucose metabolism in patients with type II diabetes and to serve as a general cellular antioxidant, among many other things. There is significant evidence that lipoic acid can be endogenously synthesized in mammalian cells, and that the inhibition of this pathway compromises cellular function and leads to death.

描述（由申请人提供）：lipoic酸是一种必不可少的含硫的辅助剂，在能量代谢中涉及的几种多烯酶配合物中发现。以其功能形式，它在指定的脂肪烯携带蛋白上的特定赖氨酸残基的Epsilon氨基相互连接。它在这些复合物中发挥作用的详细方式已有很长时间了，并且几乎可以在每个开始的生物化学教科书中找到。相比之下，只有在过去的几年中，对其生物合成的明确了解才开始出现。 lipoic酸是以其辅因子形式而不是其游离酸形式的生物合成，需要两种用于转化的蛋白质。第一个，八烷酰转移酶（LIPB）催化了八碳脂肪酰基链的转移，从八烷酰基-ACP转移到细胞中携带蛋白质的几种lipoyl。第二蛋白Lipoyl合酶（LIPA）催化了脂肪酰基基团6和8位置的两个硫原子的插入，从而提供了Lipoyl辅助因子。 Lipa是酶的激进SAM超家族的成员，它们使用[4FE-4S]和S-腺苷甲硫代氨酸来产生每个反应中中间体的高能源自由基。该提议的长期目标是在详细的分子水平上了解这些酶的工作方式。特别的焦点将针对LIPA，以准确了解插入基质中的硫原子的位置。努力将涉及细菌遗传学，瞬态状态动力学和光谱法（UV-VIS，EPR，M“ SSBAUER，SSBAUER，ENDOR和FT-ICR质谱法）。除了脂肪酸作为辅助因子中的辅助酸的参与外，众所周知，与糖代综合症相关的糖尿病与糖尿病的糖尿病相关，并且是对A的糖尿病的影响。细胞抗氧化剂，除其他许多因素外，还可以在哺乳动物细胞中内源性地合成lipoic酸，并且该途径的抑制会损害细胞功能并导致死亡。