Leishmania major: molecular modeling of cysteine proteases and prediction of new nonpeptide inhibitors.
The crystal structures of papain, cruzain, and human liver cathepsin B were used to build homology-based enzyme models of a cathepsin L-like cysteine protease (cpL) and a cathepsin B-like cysteine protease (cpB) from the protozoan parasite Leishmania major. Although structurally a member of the cathepsin B subfamily, the L. major cpB is not able to cleave synthetic substrates having an arginine in position P2. This biochemical property correlates with the prediction of a glycine instead of a glutamic acid at position 205 (papain numbering). The modeled active sites of the L. major cpB and cpL were used to screen the Available Chemicals Directory (a database of about 150,000 commercially available compounds) for potential cysteine protease inhibitors, using DOCK3.5. Based on both steric and force field considerations, 69 compounds were selected. Of these, 18 showed IC50's between 50 and 100 microM and 3 had IC50's below 50 microM. A secondary library of compounds, originally derived from a structural screen against the homologous protease of Plasmodium falciparum (falcipain), and subsequently expanded by combinatorial chemistry, was also screened. Three inhibitors were identified which were not only effective against the L. major protease but also inhibited parasite growth at 5-50 microM.
Selzer
P M
PM
Department of Pathology, University of California, San Francisco 94143, USA. Paul.Selzer@med.uni-muenchen.de
Chen
X
X
Chan
V J
VJ
Cheng
M
M
Kenyon
G L
GL
Kuntz
I D
ID
Sakanari
J A
JA
Cohen
F E
FE
McKerrow
J H
JH
D000818:Animals; D001391:Azo Compounds / Q000494:pharmacology; D001665:Binding Sites; D002401:Cathepsin B / Q000187:drug effects; D056668:Cathepsin L; D002403:Cathepsins / Q000187:drug effects; D003198:Computer Simulation; D003546:Cysteine Endopeptidases / Q000737:chemistry* / Q000187:drug effects; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology*; D015195:Drug Design; D004353:Drug Evaluation, Preclinical; D010450:Endopeptidases; D005492:Folic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D006834:Hydrazines / Q000494:pharmacology; D018320:Leishmania major / Q000201:enzymology*; D008958:Models, Molecular; D016415:Sequence Alignment; D013388:Succinimides / Q000494:pharmacology; D013463:Sulfuric Acid Esters / Q000494:pharmacology; D014344:Trypanocidal Agents / Q000737:chemistry / Q000494:pharmacology*
C109261:3,5-dichlorofolic acid; D001391:Azo Compounds; D015853:Cysteine Proteinase Inhibitors; D006834:Hydrazines; D013388:Succinimides; D013463:Sulfuric Acid Esters; D014344:Trypanocidal Agents; C109260:reactive orange; C042424:succinimidyl 4-(4-maleimidophenyl)butyrate; D005492:Folic Acid; D002403:Cathepsins; D010450:Endopeptidases; D003546:Cysteine Endopeptidases; D002401:Cathepsin B; C534281:CTSL protein, human; D056668:Cathepsin L