Purification and characterization of κ-carrageenase from a marine bacterium, Vibrio sp CA-1004

A kappa-carrageenase-producing bacterium strain CA-1004 was isolated from the surface of a marine alga and identified to Vibrio sp. The strain produced a large amount of extracellular kappa-carrageenase. A kappa-carrageenase was purified 58-fold from cell-free culture fluid by ammonium sulfate precipitation and successive chromatographies. By SDS-PAGE the enzyme was ascertained to be homogeneous and had a molecular mass of 35 kDa. The enzyme exhibited maximal activity at pH 8.0 and 40 degrees C. The pI and K-m of the enzyme were 9.2 and 3.3 mg/ml, respectively. The enzyme activity was completely inhibited by Zn2+, Pb2+ Hg2+, and N-bromosuccinimide. The enzyme hydrolyzed kappa-carrageenan and larger neocarraoligosaccharide sulfates than neocarrabiose sulfate to produce mainly neocarra-biose and -tetraose sulfates but did not act on neocarrabiose sulfate, p-nitrophenyl-alpha- and beta-D-galactopyranosides, lambda- and iota-carrageenans, agar, and porphyran.