title: Kinetic properties of missense mutations in patients with glutathione synthetase deficiency.
abstract: Patients with hereditary glutathione synthetase (GS) (EC 6.3.2.3) deficiency present with variable clinical pictures, presumably related to the nature of the mutations involved. In order to elucidate the relationship between genotype, enzyme function and clinical phenotype, we have characterized enzyme kinetic parameters of missense mutations R125C, R267W, R330C and G464V from patients with GS deficiency. One of the mutations predominantly affected the K(m) value, with decreased affinity for glycine, two mutations influenced both K(m) and V(max) values, and one mutation reduced the stability of the enzyme. This characterization agrees well with predictions based on the recently reported crystal structure of human GS. Thus our data indicate that different mutations can affect the catalytic capacity of GS by decreasing substrate affinity, maximal velocity or enzyme stability.
authors.affiliation: Department of Paediatrics, B57, Karolinska Institutet, Huddinge University Hospital, S-141 86 Huddinge, Sweden. runa.njalsson@mednut.ki.se
authors.forename: R
authors.initials: R
authors.lastname: Njålsson
authors.forename: K
authors.initials: K
authors.lastname: Carlsson
authors.forename: B
authors.initials: B
authors.lastname: Olin
authors.forename: B
authors.initials: B
authors.lastname: Carlsson
authors.forename: L
authors.initials: L
authors.lastname: Whitbread
authors.forename: G
authors.initials: G
authors.lastname: Polekhina
authors.forename: M W
authors.initials: MW
authors.lastname: Parker
authors.forename: S
authors.initials: S
authors.lastname: Norgren
authors.forename: B
authors.initials: B
authors.lastname: Mannervik
authors.forename: P G
authors.initials: PG
authors.lastname: Board
authors.forename: A
authors.initials: A
authors.lastname: Larsson
mesh_terms: D002847:Chromatography, Agarose; D005981:Glutathione Synthase / Q000737:chemistry* / Q000172:deficiency* / Q000302:isolation & purification; D006801:Humans; D007700:Kinetics; D008958:Models, Molecular; D016296:Mutagenesis; D009154:Mutation; D020125:Mutation, Missense; D011487:Protein Conformation; D017433:Protein Structure, Secondary
chemical_list: D005981:Glutathione Synthase