title: Characterization and structural modeling of a novel thermostable glycine oxidase from Geobacillus kaustophilus HTA426.
abstract: Glycine oxidase from Geobacillus kaustophilus HTA426 (GOXK) is a 43 kDa monomer flavoenzyme containing noncovalently bound FAD. The induction of the enzyme resulted in the expression of a fully soluble protein with higher specific activity than those previously reported for GOX from B. subtilis (GOXB). A study of the kinetic properties of this novel GOXK revealed the lowest KM values for most of the substrates analyzed, with the exception of D-proline which kept a similar value and had the highest Vmax value reported. The Vmax/KM ratio maintained a substrate preference of GOXK for amines of small size, like glycine, sarcosine, N-ethyl-glycine, and glycine-ethyl-ester. GOXK presented good stability at 60-70 degrees C and in alkaline media (pH 6-9.5). The putative tridimensional structure was modeled by sequence alignment and by comparing the changes between GOXK and GOXB, and the residues that could be responsible for the substrate specificity as well as those essential for the catalytic activity were found. The comparison between the possible topology of GOXK with that of GOXB showed changes at the putative interactions between monomers for the building of the tetrameric oligomerization.
authors: Department of Biochemistry and Molecular Biology-A, Faculty of Biology, University of Murcia, Campus Espinardo, E-30071 Murcia, Spain.
authors: Irene
authors: I
authors: Martínez-Martínez
authors: José
authors: J
authors: Navarro-Fernández
authors: Francisco
authors: F
authors: García-Carmona
authors: Hideto
authors: H
authors: Takami
authors: Alvaro
authors: A
authors: Sánchez-Ferrer
mesh_terms: D000594:Amino Acid Oxidoreductases / Q000737:chemistry*; D001426:Bacterial Proteins / Q000737:chemistry*; D019281:Dimerization; D004795:Enzyme Stability; D007700:Kinetics; D008958:Models, Molecular; D011487:Protein Conformation; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D001426:Bacterial Proteins; D000594:Amino Acid Oxidoreductases; C115925:glycine oxidase