Biochemical Characterization and Substrate Degradation Mode of a Novel Exotype β-Agarase from Agarivorans gilvus WHO801

Agarases are important hydrolytic enzymes for the biodegradation of agar. Understanding the degradation mode and hydrolysis products of agarases is essential for their utilization in oligosaccharide preparations. Herein, we cloned and expressed AgW1150B, a novel neoagarotetraose-forming beta-agarase from Agarivorans gilvus WHO801 that has high specific activity and a fast reaction rate. AgW1150B consists of a C-terminal glycoside hydrolase family 50 catalytic domain with two tandem noncatalytic carbohydrate-binding modules (CBMs) in the N-terminus (residues 45-214 and 236-442). AgWHSOB exhibited good enzymatic properties with high specific activity and catalytic efficiency (1523.2 U/mg and a V-max of 1700 mu mol/min/mg) under optimal hydrolysis conditions of pH 7.0 and 40 degrees C. Analysis of the hydrolysis products revealed that this enzyme is an exotype beta-agarase and that the dominant product of agarose or oligosaccharide degradation was neoagarotetraose. These findings suggest that AgVVH5OB could be utilized to yield abundant neoagarotetraose.