The biosynthesis of n‐[ 2 H 7 ] fatty acids by Arthrobacter globiformis from [U‐ 2 H 15 ] octanoic acid

The principal fatty acids present when Arthrobacter globiformis is grown on a glycine medium free of normal fatty acids were found to be the C15 and C16 anteiso fatty acids; only a small amount of the normal fatty acids (C14 and C16) were present. Cells grown on the same medium but supplemented mented with 0.1 mg/ml [U‐ 2 H 15 ]octanoic acid were found to contain an increased amount of the normal fatty acids and these fatty acids were found to be labeled with 7 deuteriums. I concluded that the octanoic acid is degraded by β‐oxidation in these cells to [U‐ 2 H 7 ] butyryl‐CoA, which then competes with 2‐methylbutyryl‐CoA for the initiation of fatty acid biosynthesis.