title: Subsite mapping of human salivary alpha-amylase and the mutant Y151M.
abstract: This study characterizes the substrate-binding sites of human salivary alpha-amylase (HSA) and its Y151M mutant. It describes the first subsite maps, namely, the number of subsites, the position of cleavage sites and apparent subsite energies. The product pattern and cleavage frequencies were determined by high-performance liquid chromatography, utilizing a homologous series of chromophore-substituted maltooligosaccharides of degree of polymerization 3-10 as model substrates. The binding region of HSA is composed of four glycone and three aglycone-binding sites, while that of Tyr151Met is composed of four glycone and two aglycone-binding sites. The subsite maps show that Y151M has strikingly decreased binding energy at subsite (+2), where the mutation has occurred (-2.6 kJ/mol), compared to the binding energy at subsite (+2) of HSA (-12.0 kJ/mol).
authors.affiliation: Department of Biochemistry, Faculty of Sciences, University of Debrecen, P.O. Box 55, Hungary. kandra@tigris.klte.hu
authors.forename: Lili
authors.initials: L
authors.lastname: Kandra
authors.forename: Gyöngyi
authors.initials: G
authors.lastname: Gyémánt
authors.forename: Judit
authors.initials: J
authors.lastname: Remenyik
authors.forename: Chandran
authors.initials: C
authors.lastname: Ragunath
authors.forename: Narayanan
authors.initials: N
authors.lastname: Ramasubbu
mesh_terms: D001665:Binding Sites; D002240:Carbohydrate Sequence; D002851:Chromatography, High Pressure Liquid; D006801:Humans; D006868:Hydrolysis; D008969:Molecular Sequence Data; D009154:Mutation; D011487:Protein Conformation; D012463:Saliva / Q000201:enzymology*; D013997:Time Factors; D014443:Tyrosine / Q000737:chemistry; D000516:alpha-Amylases / Q000737:chemistry* / Q000235:genetics*
chemical_list: D014443:Tyrosine; D000516:alpha-Amylases