BIOCHEMISTRY OF VITAMIN B12 AND FOLIC ACID COMPOUNDS

维生素 B12 和叶酸化合物的生物化学

• 批准号: 3228246
• 负责人: LARS G LJUNGDAHL
• 金额: $ 21.21万
• 依托单位: UNIVERSITY OF GEORGIA
• 依托单位国家: 美国
• 财政年份: 1979
• 资助国家: 美国
• 起止时间: 1979-12-01 至 1992-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3228246
• 关键词: Clostridium; acetates; adenosine triphosphate; autoradiography; carbon dioxide fixation; cytochrome b; electron spin resonance spectroscopy; electron transport; enzyme complex; enzyme induction /repression; enzyme mechanism; enzyme structure; ferredoxin; formates; methanol; microorganism metabolism; nickel; nutrition related tag; radiotracer; rubredoxins; selenium; spectrometry; tetrahydrofolates; tungsten; vitamin B12 compound

The proposed study will be conducted with the acetogenic bacteria Clostridium thermoaceticum, Clostridium thermoautotrophicum and Clostridium formicoaceticum. The important feature of these bacteria is their capacity to synthesize acetate from carbon dioxide. This occurs via a pathway, which is now recognized as a new autotrophic pathway of carbon dioxide fixation. It involves the reduction of carbon dioxide to formate by formate dehydrogenase and to carbon monoxide by carbon monoxide dehydrogenase. These enzymes contain tungsten, selenium and iron and nickel, zinc and iron, respectively. The role of these elements in the catalytic process will be studied using radioactive isotopes and spectrometric methods such as EPR, EXAFS, UV. The enzymes will be sequenced by cloning and DNA sequencing techniques to obtain binding sites for the metals and active sites on the enzymes. These studies will increase our understanding on how trace elements function in biological reaction catalyzed by enzymes. Formate is destined to form the methyl group of acetate. This involves several enzymes that are tetrahydrofolate- and vitamin B12-dependent. Sequencing and active site studies will be performed. These experiments will give knowledge about enzymes converting 1-carbon compounds, which are needed for DNA, RNA and protein synthesis. The acetogens when grown autotrophically must produce energy in a process involving the reduction of carbon dioxide. Several electron carriers including cytochrome b, ferredoxins, rubredoxins, and flavodoxins have been isolated from the acetogens. They also contain an ATP-ase. The possible involvement of these carriers in the electron transfer and ATP- generating processes will be studied. It is believed that these processes in the acetogens are primitive and the results would be of importance to interpret the evolution of energy producing biological systems.

拟议的研究将使用产乙酸菌进行 热醋酸梭菌 热自养菌和甲酸乙酸梭菌。 的 这些细菌的重要特征是它们能够合成 从二氧化碳中提取乙酸盐。 这是通过一种途径发生的， 现在被认为是二氧化碳的一种新的自养途径 固定 它包括将二氧化碳还原成甲酸盐 通过甲酸脱氢酶和一氧化碳通过碳 一氧化脱氢酶 这些酶含有钨， 硒和铁以及镍、锌和铁。 的作用 这些元素在催化过程中将研究使用 放射性同位素和光谱测定方法如EPR， EXAFS，UV。 这些酶将通过克隆和DNA进行测序 测序技术以获得金属的结合位点， 酶的活性位点。 这些研究将增加我们的 了解微量元素在生物体内的作用 酶催化的反应。 甲酸酯注定要形成乙酸酯的甲基。 这 包括几种酶，四氢叶酸和维生素 依赖维生素B12 测序和活性位点研究将 执行。 这些实验将提供关于 转化1-碳化合物的酶， DNA、RNA和蛋白质合成。 产乙酸菌在自养生长时，必须产生能量， 涉及减少二氧化碳的过程。 几 电子载体包括细胞色素B，铁氧化还原蛋白， rubredoxins和flavodoxins已经从 产乙酸菌 它们还含有ATP酶。 可能的 这些载体参与电子转移和ATP- 将研究生成过程。 据信这些 产乙酸菌中的过程是原始的，结果将是 对解释能源生产的演变具有重要意义 生物系统。