Identification and Characterization of a Novel Alginate Lyase VSAly7C with Potential Application for Alginate Di- and Tri-Saccharide Preparation

Brown algae are the largest-producing macroalgae, and alginate lyase plays a key role in the green degradation and high-value conversion of brown algae. This study characterized a novel alginate lyase, VSAly7C, from the marine bacterium Vibrio sp. 8-14, which belongs to the PL7_5 subfamily. Biochemical analysis suggested that VSAly7C is medium-temperature, neutral, and polyG-preferred, with enzyme activities of 2608.3 ± 27.3, 1453.2 ± 50.2, and 2545.2 ± 13.2 U/mg toward polyG, polyM, and sodium alginate, respectively. The minimal oligosaccharides VSAly7C could degrade were tetrasaccharides, and its major products were disaccharides and trisaccharides. Structural bioinformatic analysis of the VSAly7C active groove showed that the -1 to +3 subsite interaction network is crucial for determining the minimal oligosaccharides it can degrade. This study elucidates the catalytic properties, modes of action, and substrate recognition mechanisms of a novel alginate lyase, VSAly7C, which may be potentially applicable in alginate disaccharide and trisaccharide preparation.