Three‐dimesional structure of GlcNAcα1‐4Gal releasing Endo‐β‐Galactosidase from Clostridium perfringens

. Clostridium perfringens is a ubiquitous anaerobic bacterium that is commonly found not only in soil but also in the gastrointestinal tract of higher animals. Its pathogenicity has been reviewed extensively. As a major cause of gastrointestinal infections in humans and animals, C. perfringens is suspected to employ hydrolytic enzymes in the degradation of gastrointestinal mucous glycoproteins. A unique endo-galactosidase, Endo-GalGnGa, capable of releasing GlcNAc 1-4Gal from porcine gastric mucin was discovered serendipitously as a contaminant of a commercially available C. perfringens sialidase preparation. Further characterization revealed small but significant sequence similarities with known glycosidases, including several enzymes from Bacillus sp. Endo-GalGnGa has been cloned and overexpressed in Escherichia coli. Single-crystal X-ray diffraction studies of Endo-GalGnGa were undertaken in order to explain the distinctive behavior of these enzymes based on a structural model in atomic detail.