An analysis of errors in estimation of the rate of protein synthesis by constant infusion of a labelled amino acid.

Rates of protein synthesis in tissues can be calculated from the specific radioactivity of free and protein-bound amino acids at the end of a constant infusion of a labelled amino acid (Garlick, Millward & James (1973) Biochem. J. 136, 935--945]. The simplifying assumptions used in these calculations have been criticized [Madsen, Everett, Sparrow & Fowkes (1977) FEBS Lett. 79, 313--316]. A more detailed analysis using a programmable desk-top calculator is described, which shows that the errors introduced by the simplifying assumptions are small, particularly when the specific radioactivity of the free amino acid rises rapidly to a constant value.