6EXQ image
Entry Detail
PDB ID:
6EXQ
Keywords:
Title:
Crystal Structure of Rhodesain in complex with a Macrolactam Inhibitor
Biological Source:
Host Organism:
PDB Version:
Deposition Date:
2017-11-08
Release Date:
2018-04-11
Method Details:
Experimental Method:
Resolution:
2.50 Å
R-Value Free:
0.25
R-Value Work:
0.17
R-Value Observed:
0.17
Space Group:
P 1
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:Cysteine protease
Mutations:S172A
Chain IDs:A, B
Chain Length:215
Number of Molecules:2
Biological Source:Trypanosoma brucei rhodesiense
Primary Citation
Repurposing a Library of Human Cathepsin L Ligands: Identification of Macrocyclic Lactams as Potent Rhodesain and Trypanosoma brucei Inhibitors.
J. Med. Chem. 61 3350 3369 (2018)
PMID: 29590750 DOI: 10.1021/acs.jmedchem.7b01869

Abstact

Rhodesain (RD) is a parasitic, human cathepsin L (hCatL) like cysteine protease produced by Trypanosoma brucei (T. b.) species and a potential drug target for the treatment of human African trypanosomiasis (HAT). A library of hCatL inhibitors was screened, and macrocyclic lactams were identified as potent RD inhibitors (Ki < 10 nM), preventing the cell-growth of Trypanosoma brucei rhodesiense (IC50 < 400 nM). SARs addressing the S2 and S3 pockets of RD were established. Three cocrystal structures with RD revealed a noncovalent binding mode of this ligand class due to oxidation of the catalytic Cys25 to a sulfenic acid (Cys-SOH) during crystallization. The P-glycoprotein efflux ratio was measured and the in vivo brain penetration in rats determined. When tested in vivo in acute HAT model, the compounds permitted up to 16.25 (vs 13.0 for untreated controls) mean days of survival.

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