title: N-acetyl glutamate kinase from Daucus carota suspension cultures: embryogenic expression profile, purification and characterization.
abstract: In Daucus carota, N-acetylglutamate-5-phosphotransferase (NAGK; E.C. 2.7.2.8) specific activity was shown to correlate with the progression of somatic embryogenesis and was highest in the latter stages, where growth was most rapid. The enzyme was subsequently purified greater than 1200-fold using heat treatment, ammonium sulfate fractionation, gel filtration, anion exchange and dye ligand chromatography. Carrot NAGK was shown to have a subunit molecular weight of 31 kDa and form a hexamer. The Kms for NAG and ATP are 5.24 and 2.11 mM, respectively. Arginine (Arg) is a K-type allosteric inhibitor of the enzyme, and Hill coefficients in the order of 5 in the presence of Arg suggest that the enzyme is highly cooperative. D. carota NAGK does not bind to Arabidopsis thaliana PII affinity columns, nor does the A. thaliana PII increase NAGK specific activity, indicating its cellular location is probably different.
authors.affiliation: Biochemistry Division, Department of Biological Sciences, University of Calgary, 2500 University Dr. NW, Calgary, Alberta, Canada T2N 1N4.
authors.forename: Elke M
authors.initials: EM
authors.lastname: Lohmeier-Vogel
authors.forename: Natalia
authors.initials: N
authors.lastname: Loukanina
authors.forename: Tony S
authors.initials: TS
authors.lastname: Ferrar
authors.forename: Greg B G
authors.initials: GB
authors.lastname: Moorhead
authors.forename: Trevor A
authors.initials: TA
authors.lastname: Thorpe
mesh_terms: D018552:Daucus carota / Q000166:cytology / Q000201:enzymology*; D004591:Electrophoresis, Polyacrylamide Gel; D020869:Gene Expression Profiling; D017851:Phosphotransferases (Carboxyl Group Acceptor) / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D012639:Seeds / Q000201:enzymology* / Q000254:growth & development
chemical_list: D017851:Phosphotransferases (Carboxyl Group Acceptor); C018721:acetylglutamate kinase