L-Galactose dehydrogenase

Laing, W.A., Fearson, N., Bulley, S., and MacRae, E., (2004), Kiwifruit L-galactose dehydrogenase Molecular, biochemical and physiological aspects of the enzyme. Fund. Plant Biol. 31 1015-1025. 

Figure 2. Enzymic measurement of a-L-arabinan in fruit-juice concentrates, (a) Effect of time of incubation of sample with arabinofuranosidase and ndo-arabinanase. Diluted pear juice concentrate (1 10 0.1 ml) or sugar beet arabinan solution (0.1 ml) was incubated with an aliquot (0.1 ml) of arabinofuranosidase (5 units) plus ndo-arabinanase (0.2 units) at 35 C and pH 4.0. Aliquots were analysed for arabinose. (b) Arabinose determination using the NAD-Galactose Dehydrogenase method. Arabinose solution (0.2 ml, 50 digrams) was incubated with Tris-HCl buffer (2.5 ml, pH 8.6), NAD (0.1 ml, 10 m ml) and galactose dehydrogenase (20/i, 140 milliunits) at 35°C. Absorbance (340 nm) was measured after various time intervals.

Plants form ascorbate from GDP-mannose via GDP-L-galactose, L-galactose and L-galactono-1,4-lactone. The latter is oxidized to L-ascorbic acid by a mitochondrial L-galactono-1,4-lactone dehydrogenase, using cytochrome c as electron acceptor. The biosyntheis of L-ascorbic acid has been reviewed.337... 

Lindbladh, C., Persson, M., Bulow, L., and Mosbach, K. (1992). Characterization of a recombinant bifunctional enzyme, galactose dehydrogenase/bacterial luciferase,... 

An enzymic method which uses NAD-dependent L-fucose dehydrogenase can be used, in the absence of L-fucose to oxidize L-galactose liberated by hydrolysis of the polysaccharide.94... 

Enzymes, measured in clinical laboratories, for which kits are available include y-glutamyl transferase (GGT), alanine transferase [9000-86-6] (ALT), aldolase, a-amylase [9000-90-2] aspartate aminotransferase [9000-97-9], creatine kinase and its isoenzymes, galactose-l-phosphate uridyl transferase, Hpase, malate dehydrogenase [9001 -64-3], 5 -nucleotidase, phosphohexose isomerase, and pymvate kinase [9001-59-6]. One example is the measurement of aspartate aminotransferase, where the reaction is followed by monitoring the loss of NADH ... 

Ljungcrantz, P., Carlsson, H., Mansson, M. O., Buckel, P., Mosbach, K., and Bulow, L. (1989). Construction of an artificial bifunctional enzyme, beta-galactosidase/galac-tose dehydrogenase, exhibiting efficient galactose channeling. Biochemistry, 28,8786— 8792. 

---