Pseudomonas aeruginosa peptide peptidohydrolase

Abstract

The twice recrystallized proteinase (peptide peptidohydrolase) of Pseudomonas aeruginosa IFO 3080 contained 1–2 gramatoms of Ca per mole (48 400 g) of enzyme protein and insignificant amounts of the other metal ions. Some chelating agents, such as ethylenediaminetetraacetic acid and o-phenanthroline, inhibited the enzymic activity, but the inactivation at 40° or below was easily reversed either by dialysis, dilution or the addition of various metal ions such as Zn²⁺, Co²⁺, Ca²⁺, etc. The Ca content of the enzyme protein was not decreased by the reversible inactivation, showing that the inactivation was produced by masking the Ca²⁺ of the enzyme with the chelating agent. To dissociate the Ca²⁺ from the enzyme protein, the inactivation treatment by chelating agent was made at 50°, but the trial was unsuccessful, that is, reactivation was no longer observed during the autodigestion of the enzyme protein. Thus the proteinase was regarded as a Ca²⁺-metalloenzyme, in which Ca²⁺ was tightly bound to the enzyme protein.