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Characterization and structural modeling of a novel thermostable glycine oxidase from Geobacillus kaustophilus HTA426
Author(s) -
MartínezMartínez Irene,
NavarroFernández José,
GarcíaCarmona Francisco,
Takami Hideto,
SánchezFerrer Álvaro
Publication year - 2008
Publication title -
proteins: structure, function, and bioinformatics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.699
H-Index - 191
eISSN - 1097-0134
pISSN - 0887-3585
DOI - 10.1002/prot.21690
Subject(s) - chemistry , glycine , stereochemistry , enzyme , biochemistry , substrate (aquarium) , proline , sarcosine , monomer , residue (chemistry) , amino acid , organic chemistry , biology , polymer , ecology
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 K M values for most of the substrates analyzed, with the exception of D ‐proline which kept a similar value and had the highest V max value reported. The V max /K M 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°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. Proteins 2008. © 2007 Wiley‐Liss, Inc.