Krueger R D, Campbell J W, Fahrney D E
J Biol Chem. 1986 Sep 15;261(26):11945-8.
The archaebacterium Methanobacterium thermoautotrophicum was grown at 65 degrees C in H2- and Pi-limited chemostat cultures at dilution rates corresponding to 3- and 4-h doubling times, respectively. Under these conditions the steady state concentration of cyclic 2,3-diphosphoglycerate was 44 mM in the H2-limited cells and 13 mM in the cells grown under Pi limitation. Flux of Pi into the cyclic pyrophosphate pool was estimated by two 32P-labeling procedures: approach to isotopic equilibrium and replacement of prelabeled cyclic diphosphoglycerate with unlabeled compound. The results unequivocally demonstrate turnover of the phosphoryl groups; either both phosphoryl groups of the cyclic pyrophosphate leave together or the second leaves at a faster rate. The half-life of the rate-determining step for loss of the phosphoryl groups was approximately equal to the culture doubling time. The Pi flowing into the cyclic diphosphoglycerate pool accounted for 19% of the total Pi flux into Pi-limited cells and 43% of the total for H2-limited cells. The high phosphate flux through the large cyclic diphosphoglycerate pool suggests that this molecule plays an important role in the phosphorus metabolism of this methanogen.
嗜热自养甲烷杆菌在65摄氏度下，分别在氢气和磷酸盐受限的恒化器培养物中生长，稀释率分别对应3小时和4小时的倍增时间。在这些条件下，在氢气受限的细胞中，环二磷酸甘油酸的稳态浓度为44 mM，而在磷酸盐受限条件下生长的细胞中为13 mM。通过两种32P标记程序估计磷酸盐流入环焦磷酸池的通量：达到同位素平衡以及用未标记的化合物替换预先标记的环二磷酸甘油酸。结果明确表明磷酰基发生周转；环焦磷酸的两个磷酰基要么一起离开，要么第二个以更快的速率离开。磷酰基损失的速率决定步骤的半衰期大约等于培养物的倍增时间。流入环二磷酸甘油酸池的磷酸盐占流入磷酸盐受限细胞的总磷酸盐通量的19%，占氢气受限细胞总通量的43%。通过大的环二磷酸甘油酸池的高磷酸盐通量表明该分子在这种产甲烷菌的磷代谢中起重要作用。
