NADP-GLUTAMATE DEHYDROGENASE FROM THE HALOPHILIC ARCHAEON HALOFERAX-MEDITERRANEI - ENZYME-PURIFICATION, N-TERMINAL SEQUENCE AND STABILITY

An NADP(H)-specific glutamate dehydrogenase of Haloferax mediterranei has been purified to apparent homogeneity and characterised. The purif ied enzyme was stabilized by glycerol in absence of salt. Glutamate de hydrogenase from Hf. mediterranei is a hexameric enzyme with a native molecular mass of 320 kDa composed of monomers each with a molecular m ass of 55 kDa. At pH 8.5 the enzyme has K-ms of 0.018, 0.34 and 4.2 mM for NADP(+), 2-oxoglutarate and ammonium, respectively. Amino acid co mposition and sequence of the first 16 residues of the N-terminus have been determined.