Protein preparation, crystallization and preliminary X-ray crystallographic analysis of N-acetylglutamate kinase from Streptococcus mutans.

The N-acetylglutamate kinase from Streptococcus mutans was expressed in Escherichia coli in soluble form and purified to homogeneity. Crystals suitable for X-ray diffraction were obtained by hanging-drop vapor diffusion method and diffracted to 2.06 angstrom. The crystal belonged to space group P2(1)2(1)2, with unit cell parameters a = 57.19 angstrom, b =94.76 angstrom, c =47.58 angstrom. The gel filtration and initial phasing results showed that the enzyme exists as a monomer, which is different from previously reported N-acetylglutamate kinases.