Metabolic fate of exogenously supplied branched-chain amino acids in Spirodela polyrhiza

14C-labelIed L-leucine, L-valiae, or L-isoleucine was supplied to Spirodela polyrhiza (L.) Schleiden via the growth medium. Most of the radioactivity was recovered from the protein hydrolysate and the free amino acids. In both fractions the radioactivity was found exclusively in the original compound, except for valine which was partly converted to leucine. This conversion also accounted for the accumulation of leucine after growth inhibition of the duckweed by L-valine.