METABOLIC CONTROL ANALYSIS OF GLYCOLYSIS AND BRANCHING TO ETHANOL-PRODUCTION IN CHEMOSTAT CULTURES OF SACCHAROMYCES-CEREVISIAE UNDER CARBON, NITROGEN, OR PHOSPHATE LIMITATIONS
METABOLIC CONTROL ANALYSIS OF GLYCOLYSIS AND BRANCHING TO ETHANOL-PRODUCTION IN CHEMOSTAT CULTURES OF SACCHAROMYCES-CEREVISIAE UNDER CARBON, NITROGEN, OR PHOSPHATE LIMITATIONS
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DOI：
10.1016/0141-0229(94)90033-7
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发表时间：
1994-09-01
影响因子：
3.4
通讯作者：
AON, MA
中科院分区：
文献类型：
--
作者：
CORTASSA, S;AON, MA
代谢控制分析被应用到计算的糖酵解通量的酿酒酵母生长在恒化器文化的碳，氮，或磷酸盐的限制有氧的速率控制步骤。确定了对乙醇形成和三羧酸循环的分支点处的通量比以及代谢物浓度控制系数的控制。两种类型的模型进行了分析，本质上不同的葡萄糖摄取步骤，被认为是ATP和细胞外葡萄糖依赖性（模型I）或葡萄糖6-磷酸依赖性（模型II）。根据实验测定的代谢物浓度优化动力学参数。在这两种模型中，葡萄糖的摄取是糖酵解通量的主要速率控制步骤。在模型I中，摄取的控制系数在1.01和1.043之间变化。ATP消耗和ATP产生过程共同控制（C-ATPase（J）= -0.080 ~-0.0306; C-ADH（J）= -0.0069 ~-0.0144; C-TCA（J）= 0.0044 ~ 0.0144）。同时，在模型II中，通量几乎完全由吸收控制（C-IN（J）= 0.99）。独立的营养限制，生长速度和葡萄糖分解代谢的类型，速率控制步骤是相同的，只有数量上的差异。所有代谢物浓度均通过通量的相同速率控制步骤以及催化代谢物消耗的反应步骤进行控制。提出的结果点糖的吸收在酵母catenoid和控制分析的有用性，以了解代谢通量应用于生物转化过程中的显着作用。
Metabolic Control Analysis was applied to calculate the rate-controlling steps of the glycolytic flux of Saccharomyces cerevisiae growing aerobically in chemostat cultures subjected to carbon, nitrogen, or phosphate limitations. The control over the flux ratio at the branch point to ethanol formation and the tricarboxylic acid cycle as well as metabolite concentration control coefficients were determined. Two sorts of models were analyzed, essentially differing in the glucose uptake step which was considered either ATP-and extracellular glucose-dependent (model I) or glucose 6-phosphate-dependent (model II). Kinetic parameters were optimized according to the experimentally determined metabolite concentrations. In both models, glucose uptake was the main rate-controlling step of the glycolytic flux. In model I the control coefficient of the uptake varied between 1.01 and 1.043. The control was shared by ATP-consuming and -producing processes (C-ATPase(J) = -0.080 to -0.0306; C-ADH(J) = -0.0069 to -0.0144; C-TCA(J) = 0.0044 to 0.0144). Meanwhile, in model II of the flux was almost exclusively controlled by the uptake (C-IN(J) = 0.99). Independently of the nutrient limitation, growth rate and type of glucose breakdown metabolism, the rate-controlling steps were the same and only quantitative differences were noted. All metabolite concentrations were controlled by the same rate-controlling steps of the flux, and additionally, by the reaction steps catalyzing the metabolite consumption. The results presented point to the significant role of sugar uptake in yeast catabolism and the usefulness of control analysis to understand metabolic flux as applied to biotransformation processes.