[Proteases from Pseudomonas: immunologic comparison]

We studied 5 strains of Pseudomonas fluorescens, its ability to produce proteolytic enzymes and the antigenic relatedness between P. fluorescens and P. aeruginosa proteases. Cells were grown in tryptic soy broth plus 2% skim milk powder, at 4 C during 5 days. All the proteases acted on gelatin, casein, and showed limited activity on congo redelastin. By zymograms in polyacrylamide gel (PAA), one enzyme responsible of whole enzymatic activity was shown. The extracellular protease of the strain P. fluorescens ATCC 17400 was purified by ammonium sulfate precipitation (60% saturation) and chromatography on DEAE cellulose with ionic strength gradient, and Sephadex G 100. A 181 fold increase in specific activity with a recovery of 21% was obtained. PAA-sodium dodecyl sulfate revealed a single band with a molecular weight of approximately 45,700 +/- 1,000 Daltons. P. fluorescens antiprotease rabbit serum showed by immunodiffusion (ID) and countercurrent immunoelectrophoresis (CIEF) identity pattern of reaction with the homology strains studied. Rabbit sera antielastase and anti-alkaline protease of P. aeruginosa did not exhibit by ID, CIEF and immunoblotting immunological reactivity with antigen (protease) from P. fluorescens; by enzyme linked immunosorbent assay (ELISA), P. aeruginosa antielastase rabbit serum showed a weak response with P. fluorescens protease. These preliminary observations showed analogy in enzymatic functions, such as specificity, between the enzymes produced by phylogenetically related species, but the immunological studies showed very little interspecific homology.