Purification, physico-chemical characterization and sequence of a heat labile alkaline metalloprotease isolated from a psychrophilic Pseudomonas species

摘要

The psychrophilic alkaline metalloprotease (PAP) produced by a Pseudomonas bacterium isolated from Antarctica has been purified and characterized. The gene encoding PAP has been cloned and sequenced and the derived amino acid sequence shows 66% identity with the mesophilic alkaline metalloprotease from Pseudomonas aeruginosa IFO 3455 (AP). Compared to the purified AP, PAP is three times more active at 20 ℃, is very sensitive to chelating agents and is rapidly inactivated at 45 ℃. The lower thermostability of PAP can tentatively be explained by a loss of a stabilizing Ca~(2+), a decrease in the content of hydrophobic residues and a smaller aliphatic index.