title: Pyrimethamine Derivatives: Insight into Binding Mechanism and Improved Enhancement of Mutant β-N-acetylhexosaminidase Activity.
abstract: In order to identify structural features of pyrimethamine (5-(4-chlorophenyl)-6-ethylpyrimidine-2,4-diamine) that contribute to its inhibitory activity (IC50 value) and chaperoning efficacy toward β-N-acetylhexosaminidase, derivatives of the compound were synthesized that differ at the positions bearing the amino, ethyl, and chloro groups. Whereas the amino groups proved to be critical to its inhibitory activity, a variety of substitutions at the chloro position only increased its IC50 by 2-3-fold. Replacing the ethyl group at the 6-position with butyl or methyl groups increased IC50 more than 10-fold. Surprisingly, despite its higher IC50, a derivative lacking the chlorine atom in the para-position was found to enhance enzyme activity in live patient cells a further 25% at concentrations >100 μM, while showing less toxicity. These findings demonstrate the importance of the phenyl group in modulating the chaperoning efficacy and toxicity profile of the derivatives.
authors.affiliation: †Genetics and Genome Biology, SickKids, PGCRL 686 Bay Street, Toronto, Ontario M5G 0A4, Canada.
authors.forename: Michael B
authors.initials: MB
authors.lastname: Tropak
authors.affiliation: ‡Department of Chemistry, University of British Columbia, 2036 Main Mall Vancouver, British Columbia V6T 1Z1, Canada.
authors.forename: Jianmin
authors.initials: J
authors.lastname: Zhang
authors.affiliation: †Genetics and Genome Biology, SickKids, PGCRL 686 Bay Street, Toronto, Ontario M5G 0A4, Canada.
authors.forename: Sayuri
authors.initials: S
authors.lastname: Yonekawa
authors.affiliation: †Genetics and Genome Biology, SickKids, PGCRL 686 Bay Street, Toronto, Ontario M5G 0A4, Canada.
authors.forename: Brigitte A
authors.initials: BA
authors.lastname: Rigat
authors.affiliation: ‡Department of Chemistry, University of British Columbia, 2036 Main Mall Vancouver, British Columbia V6T 1Z1, Canada.
authors.forename: Virender S
authors.initials: VS
authors.lastname: Aulakh
authors.affiliation: ‡Department of Chemistry, University of British Columbia, 2036 Main Mall Vancouver, British Columbia V6T 1Z1, Canada.
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Smith
authors.affiliation: ‡Department of Chemistry, University of British Columbia, 2036 Main Mall Vancouver, British Columbia V6T 1Z1, Canada.
authors.forename: Hee-Jong
authors.initials: HJ
authors.lastname: Hwang
authors.affiliation: ‡Department of Chemistry, University of British Columbia, 2036 Main Mall Vancouver, British Columbia V6T 1Z1, Canada.
authors.forename: Marco A
authors.initials: MA
authors.lastname: Ciufolini
authors.affiliation: †Genetics and Genome Biology, SickKids, PGCRL 686 Bay Street, Toronto, Ontario M5G 0A4, Canada.|§Department of Laboratory Medicine and Pathology, University of Toronto, Medical Science Building, 1 King's College Circle, 6th Floor, Toronto, Ontario M5S 1A8, Canada.
authors.forename: Don J
authors.initials: DJ
authors.lastname: Mahuran
mesh_terms: D000544:Alzheimer Disease / Q000201:enzymology / Q000235:genetics; D002478:Cells, Cultured; D005347:Fibroblasts / Q000187:drug effects / Q000201:enzymology / Q000473:pathology; D006801:Humans; D008958:Models, Molecular; D015394:Molecular Structure; D050505:Mutant Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation / Q000235:genetics*; D011739:Pyrimethamine / Q000737:chemistry* / Q000378:metabolism*; D013329:Structure-Activity Relationship; D001619:beta-N-Acetylhexosaminidases / Q000378:metabolism*
chemical_list: D050505:Mutant Proteins; D001619:beta-N-Acetylhexosaminidases; D011739:Pyrimethamine