β-Galactose Dehydrogenase

β-Galactose Dehydrogenase plays a crucial role in galactose metabolism by catalyzing the pyridine-nucleotide-dependent dehydrogenation of β-D-galactopyranose to yield NADH and D-galactono-l,5-1actone. D-galactose dehydrogenase from P. fluorescens is a member of the oxidoreductases family. It is composed of two identical subunits and has a molecular weight of 64,000. Additionally, the enzyme contains two binding sites.

β-Galactose Dehydrogenase has been used as a reporter enzyme in neuraminidase (NA) kinetic parameters for the natural substrates 6′-Sialyl-N-acetyllactosamine (6SLN) and 3′-Sialyl-N-acetyllactosamine (3SLN).

Galactose dehydrogenase will oxidize D-galactose [K_m = 0.7 mM (30 °C, pH 9.1); relative rate = 1.00], L-arabinose (relative rate = 0.47), D-fucose (relative rate = 1.05), 2-deoxy-D-galactose (relative rate = 0.27), 2-amino-2-deoxy-D-galactose [galactosamine], (relative rate = 0.02; pH 8.6).
Galactose dehydrogenase does not oxidize L-galactose, D-arabinose, D-glucose, L-fucose, D-ribose, D-xylose, D-glucuronic acid, D-galacturonic acid or D-galactose-6-phosphate. The enzyme will use either NAD (K_m = 0.24 mM; relative rate = 1.0) or NADP (K_m = 2.3 mM; relative rate = 0.32).

Suspension in 3.2 M ammonium sulfate solution, 1 mM EDTA, pH approximately 6

Contaminants: <0.01% ADH, <0.01% ?-galactosidase, <0.1% NADH oxidase, <0.5% LDH

For life science research only. Not for use in diagnostic procedures.

Galactose dehydrogenase from Pseudomonas fluorescens (MW 64,000 D) is a dimer with subunits of equal size (subunit MW = 32,000 D).

One unit galactose dehydrogenase will oxidize 1 mol of β-D-galactose in one minute at +25 °C and pH 8.6.
The QC assay produces 1 mol of NADH per mol of galactose oxidized.