title: Barley beta-galactosidase: structure, function, heterogeneity, and gene origin.
abstract: Barley (Hordeum vulgare) beta-galactosidase is composed of a large (45 kDa) and a small (33 kDa) polypeptide. N-terminal sequencing of the polypeptides and antibody reactivity data place the barley enzyme and heterodimeric plant beta-galactosidases from jack bean, maize, and wheat in family 35 of the glycosyl hydrolases. Sequence analysis indicates the existence of a subfamily of genes coding for polypeptide precursors that are cleaved to produce the two subunits in heterodimeric beta-galactosidases. The heterogeneity of the barley holoenzyme is related, but not restricted, to the N-glycosylation of the small polypeptide. Both polypeptides are essential for the catalytic activity of the enzyme.
authors.affiliation: Laboratory of Biochemistry, School of Chemistry, Aristotle University of Thessaloniki, Greece.
authors.forename: D
authors.initials: D
authors.lastname: Triantafillidou
authors.forename: J G
authors.initials: JG
authors.lastname: Georgatsos
mesh_terms: D000595:Amino Acid Sequence; D000906:Antibodies / Q000276:immunology; D004591:Electrophoresis, Polyacrylamide Gel; D019143:Evolution, Molecular; D006031:Glycosylation; D001467:Hordeum / Q000201:enzymology* / Q000235:genetics; D008969:Molecular Sequence Data; D016415:Sequence Alignment; D020539:Sequence Analysis, Protein; D013045:Species Specificity; D001616:beta-Galactosidase / Q000737:chemistry* / Q000235:genetics / Q000276:immunology / Q000378:metabolism*
chemical_list: D000906:Antibodies; D001616:beta-Galactosidase