Weinhouse H, Benziman M
Biochem J. 1974 Mar;138(3):537-42. doi: 10.1042/bj1380537.
The metabolism of glucose and fructose was studied in resting succinate-grown cells of Acetobacter xylinum. From fructose only cellulose and CO(2) were formed by the cells, whereas from glucose, gluconate was formed much more rapidly than these two products. The molar ratio of sugar converted into cellulose to sugar converted into CO(2) was significantly greater than unity for both hexoses. The pattern of label retention in the cellulose formed by the cells from specifically (14)C-labelled glucose, fructose or gluconate corresponded to that of hexose phosphate in a pentose cycle. On the other hand, the isotopic configuration of cellulose arising from variously singly (14)C-labelled pyruvate did not agree with the operation of a pentose cycle on gluconeogenic hexose phosphate. Readily oxidizable tricarboxylic acid-cycle intermediates such as acetate, pyruvate or succinate promoted cellulose synthesis from fructose and gluconate although retarding their oxidation to CO(2). The incorporation into cellulose of C-1 of fructose was greatly increased in the presence of these non-sugar substrates, although its oxidation to CO(2) was greatly diminished. It is suggested that the flow of hexose phosphate carbon towards cellulose or through the pentose cycle in A. xylinum is regulated by an energy-linked control mechanism.
在木醋杆菌以琥珀酸为底物生长的静止细胞中研究了葡萄糖和果糖的代谢。细胞仅从果糖形成纤维素和二氧化碳，而从葡萄糖形成葡萄糖酸的速度比这两种产物快得多。两种己糖转化为纤维素的糖与转化为二氧化碳的糖的摩尔比均显著大于1。细胞由特异性（14）C标记的葡萄糖、果糖或葡萄糖酸形成的纤维素中的标记保留模式与戊糖循环中磷酸己糖的模式一致。另一方面，由各种单（14）C标记的丙酮酸产生的纤维素的同位素构型与糖异生磷酸己糖上戊糖循环的运行不一致。易氧化的三羧酸循环中间体，如乙酸、丙酮酸或琥珀酸，促进了果糖和葡萄糖酸的纤维素合成，尽管减缓了它们氧化为二氧化碳的过程。在这些非糖底物存在下，果糖C-1掺入纤维素的量大大增加，尽管其氧化为二氧化碳的量大大减少。有人提出，木醋杆菌中磷酸己糖碳流向纤维素或通过戊糖循环是由能量相关的控制机制调节的。
