Hepatitis C NS3 protease inhibition by peptidyl-alpha-ketoamide inhibitors: kinetic mechanism and structure.
A series of novel peptidyl-alpha-ketoamide compounds were evaluated as inhibitors of the deltaNS3-NS4A serine protease from the hepatitis C virus. These peptidyl-alpha-ketoamide inhibitors with Ki values ranging from 0.17 nM to 5.6 microM exhibited slow-binding inhibition. Kinetic studies established one-step kinetic mechanisms and dissociation rate constants in the 3-7 x 10(-5) s(-1) range for these compounds. The association rate constants, which ranged from 10 to 263,000 M(-1) s(-1), were responsible for the greater than four order of magnitude overall binding affinity range exhibited by this series. An X-ray crystal structure of a protease-inhibitor complex revealed an unusual interaction between the oxyanion of the adduct and the protein as well as a significant movement in the S1' region of the protein loop comprising residues 35-42. These results are quite different from peptidyl-alpha-ketoacid inhibition of HCV protease, which reportedly undergoes no notable conformational changes and proceeds with a two-step slow-binding kinetic mechanism.
Liu
Yaya
Y
Antiviral Research, Infectious Disease Research and Advanced Technology, Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, IL 60064-6217, USA. yaya.liu@abbott.com
Stoll
Vincent S
VS
Richardson
Paul L
PL
Saldivar
Ayda
A
Klaus
Jeffrey L
JL
Molla
Akhteruzzaman
A
Kohlbrenner
William
W
Kati
Warren M
WM
D000577:Amides / Q000378:metabolism*; D001665:Binding Sites; D018360:Crystallography, X-Ray; D016174:Hepacivirus / Q000201:enzymology* / Q000378:metabolism; D007700:Kinetics; D011480:Protease Inhibitors / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D013997:Time Factors; D017361:Viral Nonstructural Proteins / Q000037:antagonists & inhibitors*; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases
D000577:Amides; D011480:Protease Inhibitors; D017361:Viral Nonstructural Proteins; C084422:NS3 protein, hepatitis C virus; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases