title: Evidence for essential histidine and dicarboxylic amino-acid residues in the active site of UDP-glucose : solasodine glucosyltransferase from eggplant leaves.
abstract: Effects of several chemical probes selectively modifying various amino-acid residues on the activity of UDP-glucose : solasodine glucosyltransferase from eggplant leaves was studied. It was shown that diethylpyrocarbonate (DEPC), a specific modifier of histidine residues, was strongly inhibitory. However, in the presence of excessive amounts of the enzyme substrates, i.e. either UDP-glucose or solasodine, the inhibitory effect of DEPC was much weaker indicating that histidine (or histidines) are present in the active site of the enzyme. Our results suggest also that unmodified residues of glutamic (or aspartic) acid, lysine, cysteine, tyrosine and tryptophan are necessary for full activity of the enzyme. Reagents modifying serine and arginine residues have no effect on the enzyme activity.
authors.affiliation: Institute of Biochemistry, Warsaw University, I. Miecznikowa 1, 02-096 Warsaw, Poland.
authors.forename: Paulina
authors.initials: P
authors.lastname: Nawłoka
authors.forename: Małgorzata
authors.initials: M
authors.lastname: Kalinowska
authors.forename: Cezary
authors.initials: C
authors.lastname: Paczkowski
authors.forename: Zdzisław A
authors.initials: ZA
authors.lastname: Wojciechowski
mesh_terms: D000600:Amino Acids, Dicarboxylic / Q000737:chemistry / Q000378:metabolism*; D001665:Binding Sites; D004047:Diethyl Pyrocarbonate / Q000737:chemistry / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology; D005964:Glucosyltransferases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D006031:Glycosylation; D006639:Histidine / Q000737:chemistry / Q000378:metabolism*; D007555:Isoxazoles / Q000737:chemistry / Q000494:pharmacology; D015335:Molecular Probes / Q000737:chemistry / Q000494:pharmacology; D018515:Plant Leaves / Q000201:enzymology; D012991:Solanaceous Alkaloids / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D032323:Solanum melongena / Q000201:enzymology*; D013150:Spirostans / Q000737:chemistry / Q000378:metabolism; D014316:Tritium; D014532:Uridine Diphosphate Glucose / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D000600:Amino Acids, Dicarboxylic; D004791:Enzyme Inhibitors; D007555:Isoxazoles; D015335:Molecular Probes; D012991:Solanaceous Alkaloids; D013150:Spirostans; D014316:Tritium; C009686:N-ethyl-5-phenylisoxazolium-3'-sulfonate; D006639:Histidine; C046297:sarsasapogenin; D005964:Glucosyltransferases; C104470:UDP-glucose solasodine glucosyltransferase; C012037:solasodine; D004047:Diethyl Pyrocarbonate; D014532:Uridine Diphosphate Glucose