The isolation of hydroxylysine picrate from a gelatin hydrolysate

Abstract

Vol. 42 ACETOACETATE METABOLISM. 2 305 L-malate, citrate, a-ketoglutarate) found in solutions as a result of the interaction between acetoacetate and oxaloacetate were determined in aerobic and anaerobic experiments. The most notable effect of oxygen on the yields of various substances was a higher yield of citrate. Calculations based on the yields suggest that acetoacetate contributes towards the formation of the acids of the tricarboxylic cycle, a conclusion now firmly established by the tracer work of Buchanan et al. and of Weinhouse et al.5. Erythro-1:2-dihydroxybutyric acid was not metabolized by sheep kidney cortex whilst the threo form was slowly oxidized. In accordance with Weil-Malherbe's findings, the slowness of the oxidation exclude § this substance as an intermediate in the removal of ketone bodies.6. Measurements of the rates of ac-ketoglutarate formation from various substrates and substrate combinations showed that the tricarboxylic acids yield a-ketoglutarate more rapidly than any other substrate. This supports the assumption that oc-ketoglutarate arises via the tricarboxylic acids when formed in the presence of oxaloacetate and acetoacetate (or pyruvate). The rate of citrate formation via carboxylation of oc-ketoglutarate (Ochoa, 1945) was relatively slow in sheep kidney cortex.7. The sum of ci8aconitate plus iwocitrate was found to exceed 10-5% of the total tricarboxylic acids (maximum 49 %) under suitable conditions. It is pointed out that this finding excludes the sequence (4) (p. 302) and supports the sequence (3) (p. 301), confirming conclusions earlier drawn from tracer work.8. Itwasconfirmedthatbarium (Wieland& Rosenthal, 1943) and bicarbonate (Breusch, 1943 a, b) ions increase the yield of citrate from oxaloacetate and acetoacetate. Possible causes of this effect were investigated.