ABSTRACT
An inducible L-fucose dehydrogenase from the yeast-like fungus Pullularia pullulans was purified and studied. The enzyme catalyses the oxidation of L-fucose to L-fuconic acid possibly throught its unstable L-funcono-lactone. the enzyme was purified to hemogeneity by a sequence of protamine sulfate treatment, ammonium sulfate fractionation, gel filtration on Sephadex G-100, and DEAE-cellulose chromatography. This sequence resulted in an 87 fold purification. The apparent molecular weight determined by gel filtration and SDS polyacrilamide gel electrophoresis was 40 000. the dehydrogenase was NAD-especific and showed a high sugar substrate specificity. Of several D-and L-aldoses tested only L-fucose, L-galactose and-arabinose served as substrates. The maximum velocity for the reaction was at 33- and pH 10.5. Under these conditions, the Km values, and D-arabinose, respectively. The enzyme was strongly inhibited by thiol reagents, heavy metal ions, and was not particularly stable. At 4- it rapidly los activity, but remained active for two months when maintained at -20-. The enzyme has been used to quantativate L-fucose