title: Formation of an aspartyl phosphate intermediate in the reactions of nucleoside phosphotransferase from carrots.
abstract: The nucleoside phosphotransferase from carrots forms N-phosphorylhydroxylamine when substrates are hydrolysed in the presence of hydroxylamine. Denaturation of the enzyme after short incubation with the substrates leads to a protein, in which, after reduction with [3H]NaCNBH3 and complete hydrolysis with 6 M HCl, labelled homoserine can be detected. The first experiment provides evidence for an activated phosphorylenzyme, the second experiment shows that the intermediate is an acyl phosphate formed by a nucleophilic attack of an aspartate beta-carboxylate group.
mesh_terms: D001224:Aspartic Acid / Q000031:analogs & derivatives* / Q000378:metabolism; D001894:Borohydrides; D002852:Chromatography, Ion Exchange; D002854:Chromatography, Paper; D004563:Electrochemistry; D004590:Electrophoresis, Paper; D006714:Homoserine / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D019811:Hydroxylamine; D006898:Hydroxylamines; D010084:Oxidation-Reduction; D010770:Phosphotransferases / Q000378:metabolism*; D010944:Plants / Q000201:enzymology*; D013379:Substrate Specificity
chemical_list: D001894:Borohydrides; D006898:Hydroxylamines; C032197:beta-aspartyl phosphate; D019811:Hydroxylamine; D001224:Aspartic Acid; D006714:Homoserine; C009282:sodium cyanoborohydride; D010770:Phosphotransferases; C021892:nucleoside phosphotransferase