31P nuclear magnetic resonance studies of glycogen phosphorylase from rabbit skeletal muscle: ionization states of pyridoxal 5'-phosphate.
31P nuclear magnetic resonance (NMR) at 72.8 MHZ has been used to study glycogen phosphorylase from rabbit muscle (1,4-alpha-D-glucan:orthophosphate alpha-glucosyltransferase, EC 2.4.1.1) at concentrations as low as 25 mg/ml, using a WH-180 wide-bore superconducting spectrometer. The use of a thio analogue for 5'-AMP and arsenate for inorganic phosphate allowed the observation of three distinct forms of enzyme-bound pyridoxal 5'-phosphate at --0.2 ppm (Form I), --2 to --3 ppm (Form II), and --3.5 ppm (Form III) relative to triethylphosphate. Conversion of I to III occurs by activation of phosphorylase either by formation of a ternary complex of phosphorylase b with effector and arsenate or, more efficiently, by direct phosphorylation to give the a form of the enzyme. The ionization state and exposure to solvent of each of the three forms is inferred from the 31P NMR data.
D000249:Adenosine Monophosphate / Q000031:analogs & derivatives / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000494:Allosteric Regulation; D000818:Animals; D001149:Arsenates / Q000378:metabolism; D001665:Binding Sites; D055598:Chemical Phenomena; D002621:Chemistry; D006863:Hydrogen-Ion Concentration; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D009132:Muscles / Q000201:enzymology*; D006005:Phosphorylases / Q000378:metabolism; D011487:Protein Conformation; D011732:Pyridoxal Phosphate / Q000378:metabolism; D011817:Rabbits; D012694:Serine
D001149:Arsenates; D008024:Ligands; D000249:Adenosine Monophosphate; D012694:Serine; D011732:Pyridoxal Phosphate; D000255:Adenosine Triphosphate; D006005:Phosphorylases