title: 1,N6-etheno-AMP and 1,N6-etheno-2'-deoxy-AMP as probes of the activator site of glycogen phosphorylase from rabbit skeletal muscle.
abstract: Both 1,N6-etheno-AMP and 1,N6-etheno-2'-deoxy-AMP bind at the AMP site of phosphorylase b (1,4-alpha-D-glucan:orthophosphate alpha-glucosyltransferase, EC 2.4.1.1). Etheno-AMP induces the same activation as AMP, about 30-fold higher than the activation induced by etheno-dAMP. The fluorescence of etheno-AMP and etheno-dAMP is associated with the base moiety; therefore, when free in solution, the two derivatives have identical fluorescence properties. However, when bound to phosphorylase, the fluorescence of etheno-AMP is quenched more efficiently than the fluorescence of etheno-dAMP. This difference between the fluorescence properties of the bound nucleotides suggests that a modification in the ribose ring affects the position of the adenine in the AMP site of phosphorylase b. The observed quenching may be due to a stacking interaction between an aromatic residue and the base moiety of the bound nucleotide.
mesh_terms: D000249:Adenosine Monophosphate / Q000031:analogs & derivatives* / Q000378:metabolism; D000494:Allosteric Regulation; D000818:Animals; D001665:Binding Sites; D004789:Enzyme Activation; D009132:Muscles / Q000201:enzymology; D006005:Phosphorylases / Q000378:metabolism*; D011817:Rabbits; D013050:Spectrometry, Fluorescence; D013329:Structure-Activity Relationship
chemical_list: D000249:Adenosine Monophosphate; D006005:Phosphorylases