title: Contribution of the active site aspartic acid to catalysis in the bacterial neuraminidase from Micromonospora viridifaciens.
abstract: A recombinant D92G mutant sialidase from Micromonospora viridifaciens has been cloned, expressed and purified. Kinetic studies reveal that the replacement of the conserved aspartic acid with glycine results in a catalytically competent retaining sialidase that possesses significant activity against activated substrates. The contribution of this aspartate residue to the free energy of hydrolysis for natural substrates is greater than 19 kJ/mol. The three dimensional structure of the D92G mutant shows that the removal of aspartic acid 92 causes no significant re-arrangement of the active site, and that an ordered water molecule substitutes for the carboxylate group of D92.
authors.affiliation: Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6.
authors.forename: Jacqueline N
authors.initials: JN
authors.lastname: Watson
authors.forename: Simon
authors.initials: S
authors.lastname: Newstead
authors.forename: Veedeeta
authors.initials: V
authors.lastname: Dookhun
authors.forename: Garry
authors.initials: G
authors.lastname: Taylor
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Bennet
mesh_terms: D001224:Aspartic Acid / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites; D002240:Carbohydrate Sequence; D002384:Catalysis; D017931:DNA Primers; D009682:Magnetic Resonance Spectroscopy; D008847:Micromonospora / Q000201:enzymology*; D009439:Neuraminidase / Q000737:chemistry / Q000378:metabolism*
chemical_list: D017931:DNA Primers; D001224:Aspartic Acid; D009439:Neuraminidase