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Two Soluble forms of Glutamate Dehydrogenase Isoproteins from Bovine Brain

1995; Wiley; Volume: 233; Issue: 1 Linguagem: Inglês

10.1111/j.1432-1033.1995.340_1.x

1432-1033

Sung‐Woo Cho, Jong Weon Lee, Soo Young Choi,

Neuroscience and Neuropharmacology Research

Two soluble forms of novel glutamate dehydrogenase isoproteins, designated GDH I and GDH II, have been purified from bovine brain. GDH I and GDH II were separated on a hydroxyapatite column and eluted by a step gradient at different phosphate concentrations (30 mM and 50 mM for GDH I and GDH II, respectively). The preparations were homogeneous on SDS/PAGE. GDH I and GDH II showed similarity in their molecular sizes and are composed of six identical subunits having a molecular size of 57 500 Da. Differences between the biochemical properties of GDH I and GDH II, such as N‐terminal amino acid sequences of intact and tryptic‐digested enzymes, kinetic parameters, optimum pH and heat stability, were extensively examined in both reductive amination of α‐oxoglutarate and oxidative deamination of glutamate. The different effects of ADP on GDH isoproteins were also studied under various conditions. These results indicate that GDH I and GDH II, isolated from bovine brain, are novel and distinct polypeptides.