. Currents in biochemical research. Biochemistry -- Research; Biochemistry; Research. FRITZ LIPMANN hexose/2 *- ^^ph ph-glyceraildehydc + ph ph-glyceryl'^ph â 2 H â*â '^ph ph-glycerate â H2O ph'^'enolpyruvate â*â '^ph pyruvate -\r 1H lactate The terms '~ph, -ph, and ph characterize, respectively, the energy rich phosphate bond (12 kcal.), the ester phosphate bond (3 kcal.) and inorganic phosphate (7). Scheme i The Process Pattern of Lactic Acid Fermentation HEXOSE * ^ , )kâr^ 12 Kcal.(~ph) ad 12 Kcal.(~ph) LACTIC ACID-^. The flow line represents a projection into space of the catalytic pathway
. Currents in biochemical research. Biochemistry -- Research; Biochemistry; Research. FRITZ LIPMANN hexose/2 *- ^^ph ph-glyceraildehydc + ph ph-glyceryl'^ph â 2 H â*â '^ph ph-glycerate â H2O ph'^'enolpyruvate â*â '^ph pyruvate -\r 1H lactate The terms '~ph, -ph, and ph characterize, respectively, the energy rich phosphate bond (12 kcal.), the ester phosphate bond (3 kcal.) and inorganic phosphate (7). Scheme i The Process Pattern of Lactic Acid Fermentation HEXOSE * ^ , )kâr^ 12 Kcal.(~ph) ad 12 Kcal.(~ph) LACTIC ACID-^. The flow line represents a projection into space of the catalytic pathway a hexose molecule travels to reach the inert end product, lactic acid. Initial fission in the middle of the six-carbon chain seems to be prompted by the introduction of phosphate groups at both ends. This phosphorylation is a rather costly investment absorbing just one- half of the gross yield of energy and thus reducing the net yield by about fifty per cent. An initial investment of part of the ultimate energy yield in the operation of the process is a notable feature. It is this need of induction energy which makes the fermentative process autocatalytic. The misleading statement is often made that, in fer- mentation, one half of the hexose molecule oxidizes the other half, suggesting a dismutative process. What happens, rather, is that a hydrogen donor, after unloading of phosphate bond energy, is trans- formed into a hydrogen acceptor. This manner of manipulation is expressed in the characteristic shape of the flow lines which, in all fermentations, fold back on themselves. The bending back, to accept a pair of hydrogens released in a previous stage on the molecular flow line, together with the initial expenditure of energy to start the process, may be considered as general and dominant characteristics of anaerobic metabolism. 140. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration a
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