Carbenicillin-Hydrolyzing Penicillinases ofProteus mirabilisand the PSE-Type Penicillinases ofPseudomonas aeruginosa

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Abstract
Three carbenicillin-hydrolyzing penicillinases were found in P. mirabilis strains N-3, N-29 and GN79. The former 2 strains were isolated in 1978; strain GN79 was a stock culture isolated in 1965. These penicillinases closely resembled each other, and the PSE[Pseudomonas-specific enzyme]-1 and PSE-4 enzymes produced by P. aeruginosa, in their substrate profiles and kinetic properties for hydrolyzing various .beta.-lactams. Differences were found in their MW and isoelectric points which ranged from 22,000-27,000 and from 6.0-6.9, respectively. The antiserum against the purified penicillinase of N-29 cross-reacted with the enzyme of N-3 and inhibited its activity by > 80%. The antiserum also reacted with the PSE-1 and PSE-4 enzymes. The antiserum did not react with the penicillinase from strain GN79 and the PSE-2 and PSE-3 enzymes of P. aeruginosa. Enzyme production in N-3 and N-29 was mediated by R plasmids.