The enzyme catalyses the degradation of alginate by a beta-elimination reaction. It cleaves the (1->4) bond between beta-D-mannuronate and either alpha-L-guluronate or beta-D-mannuronate, generating oligosaccharides with 4-deoxy-alpha-L-erythro-hex-4-enuronosyl groups at their non-reducing ends and beta-D-mannuronate at the reducing end. Depending on the composition of the substrate, the enzyme produces oligosaccharides ranging from two to four residues, with preference for shorter products. cf. EC
4.2.2.11, guluronate-specific alginate lyase.
