title: Phosphinothricin analogues as inhibitors of plant glutamine synthetases.
abstract: A series of phosphinothricin derivatives with a modified methyl group, designed on the basis of the crystal structure of the complex formed by the inhibitor and the target enzyme from Salmonella typhimurium, were evaluated as potential inhibitors of plant glutamine synthetase. These compounds were previously shown to be equipotent or slightly weaker inhibitors to the lead compound against the bacterial enzyme. Because of the presence in higher plants of at least two enzyme forms with different subcellular localization and possible separate metabolic functions, plastidial and cytosolic glutamine synthetases were purified to electrophoretic homogeneity from spinach chloroplasts and cultured tobacco cells, respectively. Kinetic analysis confirmed the ability of the phosphinothricin analogues to inhibit both isoenzymes in the micromolar range, with a mechanism of a competitive type with respect to glutamate. Interestingly, some of them exerted a differential effect against either the two plant isoforms, or against the plant versus the bacterial enzyme.
authors.affiliation: Department of Biology, University of Ferrara, Italy. flg@unife.it
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Forlani
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Obojska
authors.forename: Łukasz
authors.initials: Ł
authors.lastname: Berlicki
authors.forename: Paweł
authors.initials: P
authors.lastname: Kafarski
mesh_terms: D000613:Aminobutyrates / Q000737:chemistry* / Q000494:pharmacology*; D002736:Chloroplasts / Q000201:enzymology; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005974:Glutamate-Ammonia Ligase / Q000037:antagonists & inhibitors* / Q000302:isolation & purification; D007527:Isoenzymes / Q000037:antagonists & inhibitors; D007700:Kinetics; D010944:Plants / Q000201:enzymology*; D012486:Salmonella typhimurium / Q000201:enzymology; D018724:Spinacia oleracea / Q000201:enzymology; D014026:Nicotiana / Q000201:enzymology
chemical_list: D000613:Aminobutyrates; D004791:Enzyme Inhibitors; D007527:Isoenzymes; C003121:phosphinothricin; D005974:Glutamate-Ammonia Ligase