Purification and characteristics of fucoidanase obtained from Dendryphiella arenaria TM94

Dendryphiella arenaria TM94 is an obligate marine fungus. Fucoidanase expressed by TM94 by solid state fermentation was purified. The fermented solid medium was extracted with citric acid buffer, and the extracts were precipitated by acetone and separated on Sephadex G-100 chromatography. The specific fucoidanase activity of purified enzyme was 27-fold than that of the crude enzyme. The recovery of the enzyme was 17.69%. SDS-PAGE was used to identify the purity and the molecular weight of the fucoidanase. A single band appeared on SDS-PAGE gel which suggested that relatively pure fucoidanase has been obtained. The molecular weight of fucoidanase is 180 kDa and the isoelectric point was about pH 4.4. The purified fucoidanase appeared to have the maximum enzymatic activity at pH 6.0. K-M and the maximum velocity of the enzyme was 6.56 mg center dot mL(-1) and 6.55 mg center dot mL(-1)center dot min(-1) by using fucoidan from Fucus vesiculosus as substrate. The enzyme may be a type of endo-fucoidanase which could hydrolyze high molecular weight fucoidan to low molecular weight fucoidan rather than to fucose.