An alginate lyase with high specific enzyme activity was purified from Vibrio sp. YKW-34, which was newly isolated from turban shell gut. The alginate lyase was purified by in order of ion exchange, hydrophobic and gel filtration chromatographies to homogeneity with a recovery of 7% and a fold of 25. This alginate lyase was composed of a single polypeptide chain with molecular mass of 60 kDa and isoelectric point of 5.5-5.7. The optimal pH and temperature for alginate lyase activity were pH 7.0 and 40 degrees C, respectively. The alginate lyase was stable over pH 7.0-10.0 and at temperature below 50 degrees C. The alginate lyase had substrate specificity for both poly-guluronate and poly-mannuronate units. The k(cat)/K-m value for alginate (heterotype) was 1.7 x 10(6)s(-1) m(-1). The enzyme activity was completely lost, by dialysis and restored by addition of Na+ or K+. The optimal activity exhibited in 0.1 M of Na+ or K+. This enzyme was resistant to denaturing reagents (SDS and urea), reducing reagents (beta-mercaptoethanol and DTT) and chelating reagents (EGTA and EDTA). (C) 2007 Elsevier Inc. All rights reserved.