Noncovalent active site interactions enhance the affinity and control the binding order of reversible inhibitors of the cAMP-dependent protein kinase.
The peptides, Leu-Arg-Arg-Ala-Ala-Leu-Gly-NH2, Leu-Arg-Arg-Gln-Ala-Leu-Gly-NH2, and Leu-Arg-Arg-Asn-Ala-Leu-Gly-NH2, serve as active site-directed inhibitors of the cAMP-dependent protein kinase from bovine cardiac muscle. The Asn-containing peptide is a 10-fold more potent inhibitor than its Ala- and Gln-containing counterparts. All three peptides are linear competitive inhibitors versus a peptide-based substrate and uncompetitive inhibitors versus MgATP. The enhanced inhibitory potency of the Asn-peptide, in conjunction with the observed loss of ATP-ase activity of the enzyme in the presence of the inhibitor, suggests that asparagine may serve as a through-space isostere of serine. The uncompetitive inhibition pattern displayed by amide-capped peptides versus MgATP indicates that these species bind in an ordered fashion to the cAMP-dependent protein kinase, with MgATP binding first.
Salerno
A
A
Department of Chemistry, State University of New York, Buffalo 14214.
Mendelow
M
M
Prorok
M
M
Lawrence
D S
DS
D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors; D000595:Amino Acid Sequence; D001665:Binding Sites; D004791:Enzyme Inhibitors / Q000737:chemistry*; D006860:Hydrogen Bonding; D066298:In Vitro Techniques; D007700:Kinetics; D008969:Molecular Sequence Data; D010455:Peptides / Q000494:pharmacology; D047428:Protein Kinase Inhibitors; D013329:Structure-Activity Relationship
D004791:Enzyme Inhibitors; D010455:Peptides; D047428:Protein Kinase Inhibitors; D000251:Adenosine Triphosphatases