PURIFICATION, CRYSTALLIZATION AND PRELIMINARY-X-RAY ANALYSIS OF PENICILLIN-BINDING PROTEIN-4 FROM ESCHERICHIA-COLI, A PROTEIN RELATED TO CLASS-A BETA-LACTAMASES

Crystals of the penicillin binding protein 4 (PBP4) from Escherichia c oli have been obtained at 37 degrees C from liquid to liquid diffusion experiments in capillaries. PBP4 was dissolved in a 1.0 M ammonium su lphate solution, buffered at pH 7.2, to a concentration of 5 mg/ml, an d was layered on top of a 1.6 to 2.2 M ammonium sulphate solution. Cry stals appeared within four to six weeks. They belong to space group C2 22 with cell dimensions a = 68.5 Angstrom, b = 100.5 Angstrom and c = 137.0 Angstrom, and diffract to at least 2.8 Angstrom resolution. Ther e is one molecule with a molecule mass of 49,568 Da in the asymmetric unit.