The role of unsaturated fatty acids in mitochondrial membrane functions.

oxidation via the tricarboxylic acid cycle. The metabolism of [14C]ethanolamine to fatty acids via acetate has been shown to occur in mammals (Sprinson & Coulon, 1954; Sprinson & Weliky, 1969), but not previously ina bacterium. Thedecreased incorporation of [14C]ethanolamine that occurs when an alternative N source is present is probably related to the repression by (NH4)2S04 of the phospholyase (deaminating) involved in ethanolamine catabolism to acetaldehyde (Jones et al., 1973). L-Asparaginase is found at high activity in E. caratovora (Cammack et al., 1972) but other N. sources may be deaminated less readily. Whereas N sources seem to regulate the metabolism of ethanolamine to acetaldehyde, the effect of acetate and other acetogenic C sources is likely to be the diluting-out of [14C]acetyl-CoA, derived from acetaldehyde, with non-radioactive material. Quantitative results suggest that the route from [14C]ethanolamine to the phosphatidyl base may not involve acetyl-CoA but may be more direct. Experiments with a wide variety of bacteria showed that all those capable of using ethanolamine as an N source for growth (for which vitamin BIZ was sometimes necessary) incorporated [14C]ethanolamine into cell substance, but to a variable extent. Bacteria incapable of catabolizing ethanolamine, under a variety of circumstances, appear to be incapable of utilizing it biosynthetically.