Base-catalyzed reactivation of glycogen phosphorylase reconstituted with a coenzyme-substrate conjugate and its analogues.
Glycogen phosphorylase reconstituted with pyridoxal (5')diphospho(1)-alpha-D-glucose (PLDP-Glc) is catalytically inactive but slowly converted to the active enzyme through the cleavage of the pyrophosphate linkage. A similar reaction occurs more rapidly on PLDP-Gal and -Xyl but not on PLDP-Man. Values of pKa for all the reactions are about 8.3, suggesting the participation of a common basic residue in these reactions. Based on the present and other results, it is presumed that Tyr-573 or Lys-574 acts as the base abstracting the proton from 2-hydroxyl group of the glucosyl moiety of PLDP-Glc.
Horinishi
N
N
Institute of Scientific and Industrial Research, Osaka University, Japan.
Tagaya
M
M
Fukui
T
T
D000818:Animals; D004789:Enzyme Activation / Q000187:drug effects; D006005:Phosphorylases / Q000378:metabolism*; D011732:Pyridoxal Phosphate / Q000031:analogs & derivatives* / Q000378:metabolism; D011817:Rabbits; D013329:Structure-Activity Relationship
D011732:Pyridoxal Phosphate; C032401:pyridoxal(5')diphospho(1)-glucose; D006005:Phosphorylases