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Inactivation of the catalytic subunit of bovine cAMP‐dependent protein kinase by a peptide‐based affinity inactivator
Author(s) -
Mobashery Shahriar,
Doughty Michael,
Kaiser E. T.
Publication year - 1990
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.360290118
Subject(s) - chemistry , protein subunit , peptide , dissociation constant , residue (chemistry) , protein kinase a , active site , biochemistry , enzyme , dissociation (chemistry) , stereochemistry , receptor , organic chemistry , gene
A peptide affinity inactivator, Ac‐Leu‐Arg‐Arg‐Ala‐(BrAc)Orn‐Leu‐Gly, was used as a tool to probe for active site residues in the catalytic subunit of bovine cAMP‐dependent protein kinase. The peptide inactivated the catalytic subunit in an active site‐directed and monophasic manner with a first‐order rate constant of 0.03 min −1 and a dissociation constant of 675 μ M . Studies with radioactive peptide indicated that approximately one equivalent of peptide was incorporated into each protein molecule. Protein sequencing identified the modified residue as Cys‐199. A possible location for Cys‐199 within the active site is suggested.