Formation of Fusel Alcohols From Amino Acids With Branched Chains*

The natural amino acids with branched chains, l-valine, l-leucine and l-iso-leucine, when added to a sucrose solution fermented by baker's yeast, activate the formation of isobutanol, isoamyl alcohol and/or optically active amyl alcohol. With dl-valine-4-14C, uniformly labelled l-leucine-14C and l-isoleucine-14C, it was observed that after the fermentation a considerable amount of the radioactivity was accumulated in the ether/pentane extract containing the fusel alcohols. Gas chromatographic analysis revealed that, in all the cases investigated, more than half—and with valine up to 80%—of the activity of the extract was present in the corresponding fusel alcohol fraction. The synthetic α-substituted amino acids—α-aminoisobutyric acid, α-aminomethylethylacetic acid (isovaline), α-aminodiethylacetic acid, α-aminomethyl-n-butylacetic acid and α-aminomethylisopropylacetic acid—were not metabolized by baker's yeast, nor did these acids induce the formation of fusel alcohols.