SYNTHESIS OF CELLULOSE BY ACETOBACTER-XYLINUM .3. SUBSTRATES AND INHIBITORS
SYNTHESIS OF CELLULOSE BY ACETOBACTER-XYLINUM .3. SUBSTRATES AND INHIBITORS
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DOI：
10.1042/bj0670669
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发表时间：
1957-01-01
影响因子：
4.1
通讯作者：
HESTRIN, S
中科院分区：
文献类型：
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作者：
SCHRAMM, M;GROMET, Z;HESTRIN, S
己糖（葡萄糖、果糖）、3C化合物（甘油、二羟基丙酮）和己糖酸盐（葡萄糖酸盐、2-和5-氧代葡萄糖酸盐）通过洗涤的木曲霉细胞的作用转化为纤维素。细胞的底物范围是其历史和分析条件的函数。乙酸盐、丙酮酸盐和柠檬酸盐循环中间体被氧化，但没有转化为纤维素。磷酸酯（包括葡萄糖6-磷酸、α-葡萄糖-1-磷酸、β-葡萄糖-1-磷酸和尿苷二磷酸葡萄糖）可能无法渗透到细胞（新鲜的和冻干的）中。外源添加的此类酯不形成纤维素。由葡萄糖大量形成的同化的唯一产物是纤维素。葡萄糖通过葡萄糖酸盐转化为2-和5-氧代葡萄糖酸盐。它被同化为纤维素并通过这些葡萄糖酸盐兼性氧化为二氧化碳。纤维素单体：氧化成二氧化碳的葡萄糖的摩尔比的最高值是1.7，即显着大于1。在所有情况下，己糖同时氧化释放的总能量中只有一小部分用于纤维素生产（纤维素单体：氧原子= 0.1）。外源提供的三磷酸腺苷无法维持纤维素的无氧合成。 O 2 以外的电子受体允许葡萄糖和葡萄糖酸盐的有限氧化，可能氧化为氧代葡萄糖酸盐，但这种氧化不能形成纤维素或CO 2 。从葡萄糖合成纤维素会被适当的呼吸抑制剂、巯基试剂、“麻醉剂”甚至可氧化代谢物乙酸盐和形成乙酸盐的丙酮酸盐所阻断。砷酸盐阻碍了合成；添加正磷酸盐可以减轻这种影响。虽然 10 m[图像]-氟乙酸盐阻止乙酸盐氧化并导致丙酮酸的氧化在乙酸盐水平上停止，但它允许从葡萄糖形成纤维素和二氧化碳。氟化物（10 m[图片]）会阻止纤维素的合成，但不会阻止二氧化碳的形成。 2,4-二硝基苯酚（4 m[图像]）允许氧代葡萄糖酸的产生，但阻止纤维素的形成并延缓葡萄糖中二氧化碳的形成。这些发现与以下建议一致：经洗涤的木曲霉细胞可利用替代代谢途径将外源底物转化为二氧化碳和纤维素，并且与细胞内磷酸己糖是纤维素生产中的中间体的假设一致。
Hexoses (glucose, fructose), 3 C compounds (glycerol, dihydroxyacetone) and hexonates (gluconate, 2- and 5-oxogluconate) were converted into cellulose by the action of washed cells of A. xylinum. The substrate range of the cells was a function of their history and the conditions in which they were assayed. Acetate, pyruvate and citrate-cycle intermediates were oxidized without attendant conversion into cellulose. Phosphate esters (including glucose 6-phosphate, [alpha]-glucose-1-phosphate, [beta]-glucose-1-phosphate and uridine diphosphoglucose) presumably failed to penetrate into the cells (fresh and freeze-dried). Such esters, added exogenously, did not form cellulose. The sole product of assimilation formed in substantial amount from glucose was cellulose. Glucose was converted via gluconate into 2- and 5-oxogluconate. It was assimilated into cellulose and oxidized to CO2 facultatively via these gluconates. The highest encountered valve of the molar ratio, cellulose monomer: glucose oxidized to carbon dioxide, was 1.7, i.e. significantly greater than unity. In all instances, only a small portion of the total energy liberated by concurrent oxidation of hexose was utilized for cellulose porduction (cellulose monomer: oxygen atom = 0.1). Exogenously provided adenosine triphosphate failed to sustain an anaerobic synthesis of cellulose. Electron acceptors other than O2 permitted restricted oxidation of glucose and gluconate, presumably to oxogluconates, but such oxidation did not enable formation either of cellulose or of CO2. Synthesis of cellulose from glucose was blocked by appropriate respiration inhibitors, sulfhydryl reagents, "narcotics" and even by the oxidizable metabolites acetate and acetate-forming pyruvate. Synthesis was retarded by arsentate; this effect was alleviated by added orthophosphate. Whereas 10 m[image]-fluoroacetate blocked acetate oxidation and caused that of pyruvate to cease at the level of acetate, it permitted both cellulose and carbon dioxide to be formed from glucose. Fluoride (10 m[image]) blocked the synthesis of cellulose but not the formation of CO2. 2,4-Dinitrophenol (4 m[image]) permitted oxogluconate production but blocked the formation of cellulose and retarded that of CO2 from glucose. The findings are in agreement with the suggestion that alternate metabolic pathways are available to the washed A. xylinum cell for the conversion of exogenous substrates into CO2 and cellulose and with the hypothesis than an intracellular hexose phosphate is an intermediate in cellulose production.