. The chemical activities of bacteria. Bacteria. PHOSPHORYLATION 55 7. Phosphorylation and dephosphorylation Tiie anaerobic breakdown of carbohydrate in yeast and in muscle involves the initial phosphorylation of the carbo- hydrate by a series of reactions involving adenosine-tri- phosphate and inorganic phosphate. The phosphorylated compounds then undergo a series of changes resulting in the formation of phosphopyruvic acid which is then dephos- phorylated before the final stages of fermentation take place. The fermentation of glucose by Esch. coli and related organisms has now been investiga
. The chemical activities of bacteria. Bacteria. PHOSPHORYLATION 55 7. Phosphorylation and dephosphorylation Tiie anaerobic breakdown of carbohydrate in yeast and in muscle involves the initial phosphorylation of the carbo- hydrate by a series of reactions involving adenosine-tri- phosphate and inorganic phosphate. The phosphorylated compounds then undergo a series of changes resulting in the formation of phosphopyruvic acid which is then dephos- phorylated before the final stages of fermentation take place. The fermentation of glucose by Esch. coli and related organisms has now been investigated in considerable detail (Chap. VII), and appears to involve the same basic cycle of reactions as those occurring in yeast fermentation, so that phosphorylation of glucose to hexosediphosphate precedes breakdown to simpler molecules. The intermediate stages of the phosphory- lation and the enzymes involved have not yet been worked out with bacteria, but it is highly probable that the first step is a transfer of phosphate from adenosine-tri-phosphate to the 6-position of glucose by the enzyme Hexokinase: H -\ Adenosine-di-phosphate. Many other bacterial fermentations will occur only in the presence of phosphate and are accompanied by an uptake of phosphate from the medium by the fermenting cells. The changes have seldom been investigated in detail and it is not possible to say whether phosphorylation is an invariable step in anaerobic carbohydrate breakdown. Fermentation of carbohydrate represents one of the main sources of energy for anaerobic existence. In those cases which have been worked out in detail, it appears that the incorporation of phosphate at low energy levels into organic compounds, followed by its removal at a later stage of the fermentation process from compounds in which the phosphate bond has become. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these
Size: 3006px × 831px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookcollectionbiodiversity, booksubjectbacteria
