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Base‐catalyzed reactivation of glucogen phosphorylase reconstituted with a coenzyme‐substrate conjugate and its analogues
Author(s) -
Horinishi Nobutaka,
Tagaya Mitsuo,
Fukui Toshio
Publication year - 1988
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(88)80864-0
Subject(s) - chemistry , glycogen phosphorylase , moiety , stereochemistry , conjugate , residue (chemistry) , catalysis , enzyme , pyridoxal , cleavage (geology) , substrate (aquarium) , active site , biochemistry , biology , mathematical analysis , paleontology , ecology , mathematics , fracture (geology)
Glycogen phosphorylase reconstituted with pyridoxal (5′)diphospho(1)‐α‐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 p K a 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.