title: Specificity of delta 6 desaturase--effect of chain length and number of double bonds.
abstract: Rat liver microsomes contain a delta 6 desaturase that is active not only with the unsaturated acids of 18 carbons: oleic, linoleic and alpha-linolenic but also with similar acids of 20 carbons with the double bonds in delta 9, 12 and delta 12, 15. The rate of the reaction increases with the number of double bonds of the substrate but the acids of 20 carbons are less desaturated than the corresponding homologs of 18 carbons proving that the enzyme recognizes the number and position of double bonds as well as the chain length. The investigation of the inhibitory effect of different poly-unsaturated acids suggests that the acids would not only bind to the enzyme by means of the -CoA but also by other parts of the molecule different of the active center. The geometry of the molecule would be a substantial factor.
mesh_terms: D000818:Animals; D001667:Binding, Competitive; D044943:Fatty Acid Desaturases / Q000378:metabolism*; D005260:Female; D007700:Kinetics; D008041:Linoleic Acids; D008862:Microsomes, Liver / Q000201:enzymology*; D008968:Molecular Conformation; D051381:Rats; D013379:Substrate Specificity
chemical_list: D008041:Linoleic Acids; D044943:Fatty Acid Desaturases