Crystallization and preliminary X-ray analysis of alginate lyases A1-II and A1-II′ from Sphingomonas sp. A1

摘要

Alginate lyases depolymerize alginate, a heteropolysaccharide consisting of α-­l-­guluronate and β-d-mannuronate, through a β-elimination reaction. The alginate lyases A1-II (25 kDa) and A1-II′ (25 kDa) from Sphingomonas sp. A1, which belong to polysaccharide lyase family PL-7, exhibit 68% homology in primary structure but have different substrate specificities. To determine clearly the structural basis for substrate recognition in the depolymerization mechanism by alginate lyases, both proteins were crystallized at 293 K using the vapour-diffusion method. A crystal of A1-II belonged to space group P21 and diffracted to 2.2 Å resolution, with unit-cell parameters a = 51.3, b = 30.1, c = 101.6 Å, β = 100.2°, while a crystal of A1-II′ belonged to space group P212121 and diffracted to 1.0 Å resolution, with unit-cell parameters a = 34.6, b = 68.5, c = 80.3 Å.