The remarkable hydrophobic effect of a fatty acid side chain on the microbial growth promoting activity of a synthetic siderophore

The ability of synthetic derivatives of the siderophore tripeptide of N-5-h ydroxy-N-5-acetyl-l-ornithine to promote the growth of various strains of m ycobacteria and Gram negative bacteria was found to depend significantly on the hydrophobic nature of the derivative. Although the tripeptide of N-5-h ydroxy-N-5-acetyl-l-ornithine is not normally utilized by mycobacteria, an N-terminal palmitoyl derivative mimicked natural mycobactin J in all studie s.