[Metabolism of (3-(14)C)tryptophan and (2-(14)C)alanine in cattle tissues]

In the experiments involving incubation of the liver, brain cortex, muscle and adipose tissues homogenates with [3-14C] tryptophan for an hour 43.2-89.3% of the label was found in proteins, 7.2-47.2%--in lipids, 2.6-9.4%--in CO2. Following incubation of the above-mentioned tissue homogenates with [2-14C] alanine, proteins, lipids and CO2 contain 28.8-49.3%; 22.6-31.9% and 21.6-49.3% of radioactive label, respectively. Radioactivity of lipids synthesized by the homogenates of the investigated tissues from [3-14C] tryptophan and [2-14C] alanine is 23.5-63.5 and 21.1-56.0%, respectively, the radioactivity of CO2 being 1.4-5.1 and 9.3-11.8% of the above-mentioned compounds synthesized from [1-14C] acetate. The results obtained testify to the considerable contribution of [3-14C] tryptophan and [2-14C] alanine to protein synthesis as well as to their involvement in the substrate supply of lipogenesis and energetic processes in various organs and tissues of cattle.