The Antibacterial Activity of 3-Decynoyl-N-acetylcysteamine

Abstract β-Hydroxydecanoyl-thioester dehydrase is known to be the enzyme responsible for the introduction of the double bond into the unsaturated fatty acids of Escherichia coli, and is known to be vital for bacterial growth. The powerful inhibitor in vitro of the dehydrase, 3-decynoyl-N-acetylcysteamine, possesses antibacterial activity in vivo; at 10-5 m, it completely inhibits the growth of E. coli. The following evidence suggests that this growth inhibition is due to the inactivation of β-hydroxydecanoyl-thioester dehydrase. (a) Only those acetylenic compounds which block the activity of the isolated dehydrase are effective in vivo. (b) The growth inhibition is reversible by oleic but not by palmitic acid. (c) The inhibitor causes a rapid and total cessation of the formation of unsaturated acids, well before the first noticeable decline in the growth rate. (d) The inhibitor is not active against yeast or mammalian cells, cells, which form their olefinic acids by a mechanism not involving the dehydrase.