Preliminary crystal structure determination of the alkaline protease from the Antarctic psychrophile Pseudomonas aeruginosa.

A cold alkaline protease, isolated from an Antarctic Pseudomonas aeruginosa strain, has been purified and crystallized. Large crystals were obtained in the presence of PEG 6000 at pH 7 and pH 8. They belong to the space group P2(1)2(1)2(1). A complete data set to 2.1 A resolution has been measured. The structure has been determined by the molecular replacement method using the coordinates of the mesophilic alkaline protease as a model. The molecular replacement solution displays a correlation coefficient of 0.39 and an R-factor of 0.48. Subsequent inspection of the electron density map in the active site region has confirmed the correctness of the solution. Model building and structure refinement will be initiated when the protease sequence becomes fully available. This is the second report, following one on an alpha-amylase, of the preliminary crystallographic characterization of a psychrophilic enzyme.