Inhibition by α-methyl-norvaline of the uptake of valine and leucine into haemoglobin of the chick embryo

We reported recently (Deuchar & Dryland, 1965) that α-methyl-norvaline, an amino acid whose structure resembles both valine and leucine, inhibits the uptake of these two normal amino- acids into protein in explanted chick embryos and is also itself incorporated into embryonic proteins. Since the first effect of α-methyl-norvaline that we had noted (Deuchar & Dryland, 1964) was a reduction in the quantity of haemoglobin formed in the cells of the area vasculosa, it was of special interest to see whether this inhibitor blocked the uptake of valine and/or leucine into haemoglobin in particular and whether it was at the same time taken up itself into haemoglobin. The results of experiments in which haemoglobin has been extracted from area vasculosa explants and the uptake of radioactively labelled amino acids into it has been measured, are reported here.