Abstract
It has been considered by the investigation of J. Reed et al. that a protein-bound form was the active one of lipoic acid for oxidative decarboxylation of α-ketoacid such as pyruvic or α-ketoglutaric acid. Therefore, the author studied the effect of protein composition in the diet on the biosynthesis of the protein-bound lipoic acid using Nose and Mori's method. The incorporation rate per mg N in liver mitochondrial protein (LMP) in all groups was elevated during the whole feeding period. The incorporation rate per mg N in LMP in low protein diet was higher than that in standard diet and was lower than that in protein-free diet. Therefore, it was concluded that in the low protein and protein-free diets the formation of the protein relating with the lipoic acid-activating system was lowered than that of the other liver protein. When ^<35>S-labelled lipoic acid was injected, the incorporation rate per mg N in LMP was remarkably elevated until the 1st hour but rapidly decreased thereafter.
