Hyperphenylalaninemia with defective transamination

Plasma concentrations of phenyllactic acid in phenylketonuria

“…renal clearance rates (Langenbeck et al, 1980). Rather these differences may reflect various residual activities of L-phenylalanine hydroxylase or different constants of Michaelis-Menten (Kin) for the phenylalanine transamination reaction (Blau et al, 1983). The differences should not be due to the efficacy of alternative elimination routes, for example to phenylacetylglutamine or to 2-hydroxyphenylacetic acid, because of the very high constants of Michaelis-Menten (Kin) for these routes.…”