The enzyme alginate lyase from the bacteria Sphingomonas sp. is able to degrade the polymer alginate by eliminative cleavage. Alginate is made up of beta-d-mannuronate and beta-d-glucoronate linked together by a beta-1-4 glycosidic linkage, and alginate lyase is able to cleave this linkage to release two oligosaccharides. The enzyme may have potential therapeutic applications because one of the symptoms of cystic fibrosis is a thick layer of alginate that builds up inside the lungs making breathing difficult. The bacterial species produces three types of Alginate lyase, which are non-homologous but display similar organisation in the active site, suggesting that convergent evolution may account for their similar functions. Here, the structure and mechanism of Alginate lyase III is described.
Defined by 5 residues: TYR:A-65 [auth A-68]ASN:A-188 [auth A-191]HIS:A-189 [auth A-192]ARG:A-236 [auth A-239]TYR:A-243 [auth A-246]