Synthesis of Fragments of the Peptide Component of Pseudobactin

Pseudobactin is a structurally complex and physiologically important siderophore (microbial iron chelator) from Pseudomonas putida- fluorescens. Various fragments of the unusual peptide component of pseudobactin listed below were prepared by solution-phase peptide synthesis. L -Lys· D -threo-β-OH Asp· L -Ala· D -allo-Thr· L -Ala L -Lys· D -threo-βOH Asp· L -Ala· D -allo-Thr D -threo-β-OH Asp· L -Ala· D - allo-Thr· L -Ala· D -N-OH-cycloOrn D -threo-β-OH-Asp· L -Ala· D -allo-Thr· L -Ala L -Ala· D -allo-Thr· L - Ala· D -N-OH-cycloOrn A class of related peptides named pseudomycins have shown promising antifungal activity. To examine if these peptide fragments above would elicit similar activity, the fragments were tested and found to have no antifungal activity in limited bioassays.