On the method of formation of pyruvic acid by barley

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Abstract
Cell-free barley saps, pressed out after freezing at [long dash]12CC, were incubated for 48 hours at 30[degree] C in the presence of thymol and 1-naphthol-2-sulphonic acid. These gave rise to little or no pyruvic acid when incubated alone, in spite of their content of glucose and fructose. Additions of sucrose or adenylic acid separately to saps of low sugar-content gave no more than traces of pyruvic acid. Addition of sucrose or glucose simultaneously with adenylic acid led to the formation of quantities of pyruvic acid which were readily isolated and identified as the 2, 4 dinitrophenylhydrazone. Hexosedi-phosphate and phosphoglycerate were converted to pyruvic acid without addition of adenylic acid. The presence of [image]/40 NaF markedly inhibited the formation of the pyruvic hydrazone from hexosediphosphate. This inhibition was confirmed, using Straub''s colorimetric o-oxybenzyl pyruvate method of estimation. Lactic acid was oxidized to pyruvic acid in the presence of ascorbic acid and oxygen. These results are taken to indicate the catalysis of the following reactions by barley saps, the heavy arrows showing the reactions actually performed experimentally. [image] Evidence is thus afforded that a higher plant may convert sugars to pyruvic acid by a phosphorylating cycle similar, at least in outline, to the reactions of alcoholic fermentation in yeast.