Tiie Journal of Biological Chemibtry

Pork liver has previously been reported to contain a soluble enzymatic pathway which converts L-fucose to 2-keto-3deoxy-L-fuconate and D-arabinose to 2-keto-3-deoxy-Darabonate. We now report the isolation from pork liver of a soluble NAD+-dependent dehydrogenase which acts on both 2-keto-3-deoxy-L-fuconate and 2-keto-3-deoxy-D-arabonate. This enzyme has been purified to homogeneity by a five-step procedure; the final step involved affinity chromatography on NAD+-agarose. A purification factor of about 3000-fold was achieved with a yield of over 20%. The enzyme was r 4 II HO-f-H r To L-fucose Ho-Y-H 0 II--C--OH dehydrogenase 0 II-(+011 a precursor for these important substances (5-8), and a great deal of information has been accumulated on the incorporation of fucose into macromolecules (9, 10). Radioactive fucose is considered art excellent precursor for the study of glycoprotein biosynthesis hecause it is not converted to other sugars (11-15) ; however, evidence has been obtained that free fucose can be oxidized in the animal body (16). Although a pathway for L-fucase degradation has been described in microorganisms (17), the catabolic fate of L-fucose in higher animals is as yet unknown. \Ve have described the following reactions in the soluble fraction of pork liver (18-20) :