Iron-chelating substances and inflammation

The effect of Pseudomonas aeruginosa alkaline protease (AP), elastase (Ela), and the elastase from polymorphonuclear leukocytes (PMN Ela) on iron acquisition of pyoverdin from human transferrin and lactoferrin at physiologic pH was investigated. Incubation of iron-loaded transferrin with iron-free pyoverdin for 10 h at 40 degrees C in the presence of Ela yielded pyoverdin-iron(III) complex, in contrast to incubations of transferrin with pyoverdin alone, AP, or PMN Ela. Sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis of the incubations revealed fragmentation of transferrin by Ela in peptides smaller than 14,000 daltons, whereas AP and PMN Ela cleaved transferrin in fragments of 49,000 d and 43,000 d, respectively. Incubations of lactoferrin with the proteases and pyoverdin or pyoverdin alone did not result in iron acquisition by pyoverdin; however, lactoferrin was fragmented by Ela and AP.