Creatine kinase is a member of the phosphagen kinase family, which catalyzes the reversible phosphoryl transfer reaction that occurs between ATP and creatine to produce ADP and phosphocreatine. Here, three structural aspects of humanbrain-type-creatine-kinase (hBB-CK) were identified by X-ray crystallography: the ligand-free-form at 2.2 Å ; the ADPMg 2+ , nitrate, and creatine complex (transition-state-analogue complex; TSAC); and the ADP-Mg 2+ -complex at 2.0 Å . The structures of ligand-bound hBB-CK revealed two different monomeric states in a single homodimer. One monomer is a closed form, either bound to TSAC or the ADP-Mg 2+ -complex, and the second monomer is an unliganded open form. These structural studies provide a detailed mechanism indicating that the binding of ADP-Mg 2+ alone may trigger conformational changes in hBB-CK that were not observed with muscle-type-CK.

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Fatty acid-CoA racemase plays an important role in the beta-oxidation of branched-chain fatty acids and fatty-acid derivatives as it catalyzes the conversion of several (2R)-branched-chain fatty acid-CoAs to their (2S)-stereoisomers. Fatty acid-CoA racemase from Mycobacterium tuberculosis H37Rv has been purified to homogeneity and crystallized by the hanging-drop vapour-diffusion method with polyethylene glycol 4000 as precipitant. The crystals belong to the trigonal space group P3(1) or P3(2), with unit-cell parameters a = b = 109.56, c = 147.97 A. The asymmetric unit contains six monomers, corresponding to a VM value of 2.15 A3 Da(-1). A complete native data set has been collected at 2.7 A resolution using a synchrotron-radiation source.

Glutamate racemase catalyzes the conversion of L-glutamic acid to D-glutamic acid and vice versa. Since D-glutamic acid is one of the essential amino acids present in peptidoglycan, glutamate racemase has been considered to be an attractive target for the design of new antibacterial drugs. Glutamate racemase from Lactobacillus fermenti has been crystallized by the hanging-drop vapour-diffusion method using polyethylene glycol 8000 as a precipitant. The crystals belong to the orthorhombic space group C222(1), with unit-cell parameters a = 98.32, b = 184.09, c = 45.99 A. The asymmetric unit contains one molecule, corresponding to a VM value of 1.84 A3 Da(-1). A complete data set has been collected from the native enzyme at 2.28 A resolution using a synchrotron-radiation source.

The tRNA-specific adenosine deaminase from the pathogenic bacteria Streptococcus pyogenes (spTAD) has been overexpressed in Escherichia coli and crystallized in the presence of Zn 2+ ion at 295 K using ammonium sulfate as a precipitant. Flash-cooled crystals of spTAD diffracted to 2.0 Å using 30%(v/v) glycerol as a cryoprotectant. X-ray diffraction data have been collected to 2.0 Å using synchrotron radiation. The crystal belongs to the tetragonal space group P4 2 2 1 2, with unit-cell parameters a = b = 81.042, c = 81.270 Å . The asymmetric unit contains one subunit of spTAD, with a corresponding crystal volume per protein weight (V M ) of 3.3 Å 3 Da À1 and a solvent content of 62.7%.