Cyclopropene fatty acids: metabolism and analysis. : I. Inhibition of saturated fatty acyl desaturase by cyclopropene fatty acids

Abstract

Rats maintained on a fat free diet were given methyl stearate 1-¹�C dissolved in corn oil or Sterculia foetida oil (cyclopropene fatty acid content over 60%) and the desaturation of stearic to oleic acid was studied. There was a very high degree of conversion of stearic to oleic acid in the corn oil fed group, whereas, in the Sterculia foetida oil given group the desaturation was inhibited. Pronounced inhibition was observed when the amount of Sterculia foetida oil was increased. The effect of cyclopropene fatty acids on the desaturation of stearic acid 1-¹�C was studied with a crude preparation of the fatty acyl desaturase obtained from rat liver. Almost complete inhibition was produced with a concentration of 2x10�³ [micro]moles of cyclopropene fatty acids. Fatty acyl desaturase was found to be a sulfhydryl sensitive enzyme. It is inhibited by p-chloromercuribenzoate, iodoacetate and N-ethylmaleimide. The inhibition caused by p-chloromercuribenzoate could be reversed by the addition of 2-mercaptoethanol. The inhibition caused by cyclopropene fatty acids could not be reversed by the addition of 2-mercaptoethanol. ...