Biosynthesis of Heme and Chlorophyll Precursors

;​R o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o4 @ 0 1 2 3 4 5 6 7 8 9：F Microsoft Word 6.0文档MSWordDoc。6;​四吡咯色素由一系列生物分子组成，包括血红素、叶绿素、胆磷脂和维生素B12。这些色素在呼吸和光合作用过程中起着必不可少的作用，并且在其他重要的酶反应中也作为辅助因子存在。所有的四吡咯都是由氨基乙酰丙酸（ALA）作为其第一个承诺成员的分支生物合成途径产生的。该项目的长期目标是了解植物和藻类中催化ALA形成的酶的结构、作用机制和调控，以及ALA的形成如何控制这些生物的光合色素含量。为了实现这些目标，人们最近一直致力于利用莱茵衣藻独特的遗传和生化潜力。目前已克隆出两个光调节基因，编码催化ALA形成和利用的酶，这些基因正被用于研究酶的机制和调控。本文拟分离纯化ala形成途径中的酶，研究其物理动力学性质、辅因子需求、反应机制和可能的酶相互作用，研究变构调节剂对酶活性的调节，并确定酶丰度随光照和细胞发育状态的变化。利用克隆基因作为分子探针，研究细胞在适应光的过程中，细胞的发育过程以及叶绿素生物合成途径组分的调控和表达机制。叶绿素是植物吸收阳光转化为维持地球上所有生命的生物能所必需的生物色素。这个研究项目的目标是确定植物用来进行叶绿素形成的初始步骤的生化反应，并了解植物如何控制这些反应以实现它们有效利用阳光能量的能力。*** * Oh +' 0 ' S u m m a I I o o o m a o o o o o o o o o o o o o o o o o o$ H l D H R:\WWUSER\TEMPLATE\NORMAL。DOT代谢生化Shelley A. Graves Shelley A. Graves @ M wA @ M wA @ f# Microsoft Word 6.0;e = e j j j j j j j j j j H # A 7 T L j j j四吡咯色素是一类生物分子，包括血红素、叶绿素、胆磷脂和维生素B12。这些色素在呼吸和光合作用过程中起着必不可少的作用，并且在其他重要的酶反应中也作为辅助因子存在。所有的四吡咯都是由氨基乙酰丙酸（ALA）作为其第一个承诺成员的分支生物合成途径产生的。该项目的长期目标是了解催化ALA形成的酶的结构、作用机制和调控

; R o o t E n t r y F ÕwA C o m p O b j b W o r d D o c u m e n t O b j e c t P o o l wA wA 4 @ 0 1 2 3 4 5 6 7 8 9 : F Microsoft Word 6.0 Document MSWordDoc Word.Document.6 ; 9506901 Beale Tetrapyrrole pigments comprise a family of biomolecules including hemes, chlorophyll, bilins, and vitamin B12. These pigments function as essential components in the processes of respiration and photosynthesis, and also exist as cofactors in other important enzyme reactions. All tetrapyrroles arise from a branched biosynthetic pathway that has (-aminolevulinic acid (ALA) as its first committed member. The long term goals of this project are to understand the structure, mechanisms of action, and regulation of the enzymes that catalyze ALA formation in plants and algae, and how ALA formation controls the photosynthetic pigment content of these organisms. Efforts have recently been directed to exploiting the unique genetic and biochemical potentials of the unicellular alga Chlamydomonas reinhardtii to achieve these goals. Two light regulated genes have been cloned that encode enzymes which catalyze the formation and utilization of ALA, and these genes are being used to study enzyme mechanisms and regulation. It is proposed to isolate and purify the enzymes mf the ALA-forming pathway , to characterize their physical and kinetic properties, their cofactor requirements, their reaction mechanisms and possible enzyme interactions, to study the regulation of enzyme activity by allosteric modulators, and to determine changes in the enzyme abundance in response to light and cellular developmental status. Using cloned genes as molecular probes, cellular development processes, and mechanisms of regulation and expression of components of the chlorophyll biosynthetic pathway will be studied during adaptation of the cells to light. %%% Chlorophyll is the essential biological pigment which plants use to harvest sunlight for conversion into the biological energy that sustains all life on earth. The goals of this research project are to determine the biochemical reactions that plants employ to carry out the initial steps of chlorophyll formation, and to understand how plants control these reactions to achieve their ability to efficiently use the energy in sunlight. *** Oh +' 0 S u m m a r y I n f o r m a t i o n ( / $ H l D h R:\WWUSER\TEMPLATE\NORMAL.DOT METABOLIC BIOCHEMISTRY Shelley A. Graves Shelley A. Graves @ M wA @ @ M wA @ F # Microsoft Word 6.0 3 ; e = e j j j j j j j H # A 7 T L j j j j j ~ j j j j 9506901 Beale Tetrapyrrole pigments comprise a family of biomolecules including hemes, chlorophyll, bilins, and vitamin B12. These pigments function as essential components in the processes of respiration and photosynthesis, and also exist as cofactors in other important enzyme reactions. All tetrapyrroles arise from a branched biosynthetic pathway that has (-aminolevulinic acid (ALA) as its first committed member. The long term goals of this project are to understand the structure, mechanisms of action, and regulation of the enzymes that catalyze ALA formation in