Open AccessNADP + ‐dependent glutamate dehydrogenase from the obligate methylotroph methylobacillus flagellatum
Author(s) -
Kiriukhin M.Y.,
Detkov S.Y.,
Baev M.V.,
Tsygankov Y.D.
Publication year - 1992
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1992.tb05082.x
Subject(s) - glutamate dehydrogenase , methylotroph , deamination , enzyme , amination , ammonium , chromatography , biochemistry , chemistry , sepharose , dehydrogenase , glutamate synthase , size exclusion chromatography , biology , glutamate receptor , catalysis , organic chemistry , receptor
NADP‐dependent glutamate dehydrogenase (GDH; E.C.1.4.1.4) was purified from an obligate methylotroph Methylobacillus flagellatum using ammonium sulphate precipitation, DEAE‐Sepharose and dye‐ligand Procion red HE3B column chromatography and Sephacryl S‐200 gel‐filtration. The M r of the native enzyme was estimated to be 300 000 (±5000). The enzyme consists of six identical subunits with an M r of 47 000 (±3000) (SDS‐PAGE). The enzyme has a pH optimum of 8.0 when participating in amination and 9.5 in deamination. Michaelis‐Menten kinetics were observed for both reactions. The apparent K m values were 1.33 mM, 0.032 mM, 11.5 mM, 7.0 mM and 0.014 mM for α‐ketoglutarate, NADPH, NH 4 + , glutamate and NADP + , respectively. The enzyme was highly specific for all the substrates and was insensitive to inhibitors. It plays an exclusively anabolic role in the cells.