title: Inhibition of the reductive activation of a valyl-tRNA synthetase from yeast by unsaturated fatty acids and associated observations on newly found lipophilic substances from yeast.
abstract: The reductive activation of a valyl-tRNA synthetase from yeast is strongly inhibited by 1-30 microM unsaturated fatty acids, and the inhibition is antagonized by 10-100 microM saturated fatty acids. Diethylstilbestrol also inhibits the activation. The possibility that unesterified palmitoleic and oleic acids are bona fide regulatory effectors is supported by a dramatic inverse relation between their cellular content and the growth rate of commercial bakers' yeast. An increase in the ratio of unsaturated to saturated acids with slowing growth in a laboratory strain, S288C, also supports the regulatory hypothesis. The free fatty acids are extracted into slightly acidified 50% alcohol together with traces of numerous novel lipophilic substances. One of these is suggested to function as a cofactor in conjunction with a heat-stable polypeptide that activates valyl-tRNA synthetase.
mesh_terms: D000604:Amino Acyl-tRNA Synthetases / Q000378:metabolism*; D004789:Enzyme Activation; D005231:Fatty Acids, Unsaturated / Q000502:physiology*; D007700:Kinetics; D010084:Oxidation-Reduction; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000254:growth & development; D013329:Structure-Activity Relationship; D014637:Valine-tRNA Ligase / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D005231:Fatty Acids, Unsaturated; D000604:Amino Acyl-tRNA Synthetases; D014637:Valine-tRNA Ligase