BIOLOGICAL ASYMMETRY OF GLYCEROL AND FORMATION OF ASYMMETRICALLY LABELED GLUCOSE

Abstract

Cumulative experiments of many investigators have demonstrated that labeled COz, carboxyl-labeled acetate, carboxyl-labeled intermediates of the glycolytic and tricarboxylic acid cycle, and fatty acids that give rise to carboxyl-labeled "acetate" all yield 3,4-labeled glucose when fed to rats.95 per cent or more of the tracer is present in these positions.From this fact stems much of the usefulness of the tracer distribution pattern of glycogen as an indicator of intermediary metabolism (l).'The fact that none of the fixed CO2 was in the 1 and 6 positions led Wood et al. ( 2) to conclude that symmetrical S-carbon compounds were not intermediates in the conversion of CO2 to glycogen by the animal or in the bacterial degradation of the glucose.Dihydroxyacetone and its diphosphate ester were cited as intermediates that could be excluded.This was prior to the Ogston hypothesis (3) and its confirmation (4, 5), but these compounds can be excluded even when considered in terms of the Ogston hypothesis, since each compound has two planes of symmetry and thus cannot give rise to an asymmetrical distribution of tracer (6).Glycerol on the other hand possesses only one such plane and may be treated asymmetrically by an