A bacterial strain LL1 producing kappa-carrageenase was isolated from the decayed seaweed collected from Yellow Sea, China and identified as Pseudoalteromonas porphyrae. The extracellular kappa-carrageenase in the supernatant of cell culture of the marine bacterium P. porphyrae LL1 was purified to homogeneity with a 202.6-fold increase in specific kappa-carrageenase activity as compared to that in the supernatant by ultrafiltration, gel filtration chromatography, and anion-exchange chromatography. According to the data from sodium dodecyl sulfatepolyacrylamide gel electrophoresis, the molecular mass of the purified enzyme was estimated to be 40.0 kDa. The purified enzyme could actively convert kappa-carrageenan into tetrasaccharides, but poorly convert lambda-carrageenan. The optimal pH and temperature of the purified enzyme were 8.0 and 55 degrees C, respectively. The enzyme was significantly stimulated by Mg(2+) and Ba(2+). The enzyme was inhibited by phenylmethylsulfonyl fluoride (PMSF), iodoacetic acid, EDTA, EGTA and 1,10-phenanthroline. The K(m) and V(max) values of the purified enzyme for kappa-carrageenan were 4.4 mg/ml and 0.1 mg/min ml, respectively. The amino acid sequence (NPQPHIAKPGQTWILQEKRS) of N-terminus of the purified enzyme was identical to that of N-terminus of the deduced protein encoded by the gene encoding kappa-carrageenase cloned from the marine bacterium. (C) 2010 Elsevier Ltd. All rights reserved.