Julius White

The conversion of L-valine to glucose and glycogen in the rat.

Abstract l -Valine labeled in the methyl groups has been fed to fasting as well as to phlorizinized rats. Glycogen and glucose have been isolated and degraded. The glucose and glycogen were found to be uniformly labeled and a possible explanation for this observation is given. It was shown that, depending on the level of l -valine administration, up to 38% of the isotope was expired as carbon dioxide. At higher levels of administration a considerable percentage (about 15% in 8 hr.) of the isotope was excreted in the urine.

Evidence for a three-carbon acid intermediate in the metabolism of valine

Abstract l -Valine-β-C13 has been fed to fasted rats and the glycogen isolated and degraded. Relatively high concentrations of isotope in the 1,6- and 2,5-positions indicate that the amino acid is metabolized to a 3-carbon acid which can be utilized for glycogen formation. Evidence is presented which points to propionate as the precursor of pyruvate.

The conversion of D-valine to glycogen in the rat.

Summary d -Valine labeled in the methyl groups with C 13 was administered to fasting rats. Glycogen was isolated and degraded. d -Valine is converted to glycogen in the fasting rat and a comparison of the extent of this conversion with that of the l -isomer is made. Qualitatively the two isomers appear to be converted to glycogen in the same way, but quantitatively the l -isomer is utilized about twice as fast as the d -isomer.