title: Organic azide inhibitors of cysteine proteases.
abstract: Cysteine proteases are crucial regulatory enzymes in human physiology and disease. Inhibitors are usually designed with reactive electrophiles to covalently bond to the catalytic cysteinyl sulfur, and consequently they also indiscriminately interact with biological thiolates and other nucleophiles, leading to toxic side effects in vivo. Here we describe an alternative to using reactive electrophiles, demonstrating the use of a much less reactive azidomethylene substituent (-CH2-N3) that confers potent inhibition of cysteine proteases. This new approach resulted in potent, reversible, competitive inhibitors of caspase-1 (IC50 < 10 nM), with significant advantages over aldehydes such as high stability in vitro to thiols (10 mM dithiothreitol (pH 7.2), 20 mM glutathione (pH 7.2, 9, 11)) and aqueous media, as well as some highly desirable druglike features. It was also demonstrated that azides can be incorporated into inhibitors of other caspases (e.g. 3, 8) and cathepsins (e.g. K, S, B), indicating the versatility of this valuable new approach to cysteine protease inhibition.
authors.affiliation: Centre for Drug Design and Development, Institute for Molecular Bioscience, University of Queensland, Brisbane, Qld 4072, Australia.
authors.forename: Giang Thanh
authors.initials: GT
authors.lastname: Le
authors.forename: Giovanni
authors.initials: G
authors.lastname: Abbenante
authors.forename: Praveen K
authors.initials: PK
authors.lastname: Madala
authors.forename: Huy N
authors.initials: HN
authors.lastname: Hoang
authors.forename: David P
authors.initials: DP
authors.lastname: Fairlie
mesh_terms: D000447:Aldehydes / Q000737:chemistry / Q000494:pharmacology; D001386:Azides / Q000737:chemistry* / Q000494:pharmacology*; D001665:Binding Sites; D020170:Caspase 1 / Q000378:metabolism; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors / Q000737:chemistry* / Q000494:pharmacology*; D007659:Ketones / Q000737:chemistry / Q000494:pharmacology; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D013329:Structure-Activity Relationship
chemical_list: D000447:Aldehydes; D001386:Azides; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; D007659:Ketones; D020170:Caspase 1