Gibbs M, Gfeller R P, Chen C
Institute for Photobiology of Cells and Organelles, Brandeis University, Waltham, Massachusetts 02254.
Plant Physiol. 1986 Sep;82(1):160-6. doi: 10.1104/pp.82.1.160.
The anaerobic photodissimilation of acetate by Chlamydomonas reinhardii F-60 adapted to a hydrogen metabolism was studied utilizing manometric and isotopic techniques. The rate of photoanaerobic (N(2)) acetate uptake was approximately 20 mumoles per milligram chlorophyll per hour or one-half that of the photoaerobic (air) rate. Under N(2), cells produced 1.7 moles H(2) and 0.8 mole CO(2) per mole of acetate consumed. Gas production and acetate uptake were inhibited by monofluoroacetic acid (MFA), 3-(3',4'-dichlorophenyl)-1,1-dimethylurea (DCMU) and by H(2). Acetate uptake was inhibited about 50% by 5% H(2) (95% N(2)). H(2) in the presence of MFA or DCMU stimulated acetate uptake and the result was interpreted to indicate a transition from oxidative to reductive metabolism. Carbon-14 from both [1-(14)C]- and [2-(14)C]acetate was incorporated under N(2) or H(2) into CO(2), lipids, and carbohydrates. The methyl carbon of acetate accumulated principally (75-80%) in the lipid and carbohydrate fractions, whereas the carboxyl carbon contributed isotope primarily to CO(2) (56%) in N(2). The presence of H(2) caused a decrease in carbon lost from the cell as CO(2) and a greater proportion of the acetate was incorporated into lipid. The results support the occurrence of anaerobic and light-dependent citric acid and glyoxylate cycles which affect the conversion of acetate to CO(2) and H(2) prior to its conversion to cellular material.
利用测压法和同位素技术，对适应氢代谢的莱茵衣藻F-60进行乙酸盐厌氧光解作用的研究。光厌氧（N₂）条件下乙酸盐的摄取速率约为每毫克叶绿素每小时20微摩尔，即光需氧（空气）速率的一半。在N₂条件下，每消耗1摩尔乙酸盐，细胞产生1.7摩尔H₂和0.8摩尔CO₂。一氟乙酸（MFA）、3-（3'，4'-二氯苯基）-1，1-二甲基脲（DCMU）和H₂抑制气体产生和乙酸盐摄取。5% H₂（95% N₂）使乙酸盐摄取约受50%的抑制。在MFA或DCMU存在时，H₂刺激乙酸盐摄取，其结果被解释为表明从氧化代谢向还原代谢的转变。在N₂或H₂条件下，来自[1-¹⁴C]-和[2-¹⁴C] -乙酸盐的¹⁴C被掺入到CO₂、脂质和碳水化合物中。乙酸盐的甲基碳主要（75 - 80%）积累在脂质和碳水化合物部分，而羧基碳在N₂条件下主要将同位素贡献给CO₂（56%）。H₂的存在导致细胞作为CO₂损失的碳减少，并且更大比例的乙酸盐被掺入脂质中。这些结果支持厌氧和光依赖的柠檬酸循环和乙醛酸循环的存在，这些循环在乙酸盐转化为细胞物质之前影响乙酸盐向CO₂和H₂的转化。
