title: Affinity selection to papain yields potent peptide inhibitors of cathepsins L, B, H, and K.
abstract: Endogenous cysteine proteases were given much attention lately, as their role in a variety of pathophysiological disorders became evident. Amongst them cathepsins, which are thought to be implicated in mediation of osteoporosis, cancer progression, atherosclerosis, and many other conditions, are of considerable interest as drug targets. In the presented work, papain was chosen as a model cysteine protease and panning protocol was optimized for selection of papain-binding phage-displayed peptides from a commercially available combinatorial peptide library. Different selection strategies were applied in order to select high-affinity binders. Ultimately, five cyclic peptides (CNWAAGYNCGGGS-NH2, CWSMMGFQCGGGS-NH2, CWEWGGWHCGGSS-OH, CNWTLGGYKCGGGS-NH2 (all cyclized through formation of intramolecular disulphide bond), and GNWTLGGYKGG (cyclized head-to-tail)) were synthesized and tested for inhibitory activity towards papain and human cathepsins L, B, H, and K. The peptides possess inhibitory constants in the low micromolar to mid-nanomolar range and exhibit certain selectivity for different lysosomal cysteine proteases included in this study.
authors.affiliation: Faculty of Pharmacy, Department of Pharmaceutical Biology, University of Ljubljana, Askerceva 7, SI-1000 Ljubljana, Slovenia. tomaz.bratkovic@ffa.uni-lj.si
authors.forename: Tomaz
authors.initials: T
authors.lastname: Bratkovic
authors.forename: Mojca
authors.initials: M
authors.lastname: Lunder
authors.forename: Tatjana
authors.initials: T
authors.lastname: Popovic
authors.forename: Samo
authors.initials: S
authors.lastname: Kreft
authors.forename: Boris
authors.initials: B
authors.lastname: Turk
authors.forename: Borut
authors.initials: B
authors.lastname: Strukelj
authors.forename: Uros
authors.initials: U
authors.lastname: Urleb
mesh_terms: D000595:Amino Acid Sequence; D002401:Cathepsin B / Q000037:antagonists & inhibitors; D056655:Cathepsin H; D056657:Cathepsin K; D056668:Cathepsin L; D002403:Cathepsins / Q000037:antagonists & inhibitors*; D003546:Cysteine Endopeptidases; D015853:Cysteine Proteinase Inhibitors / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology*; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D008024:Ligands; D010206:Papain / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D019151:Peptide Library; D010456:Peptides, Cyclic / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology*
chemical_list: D015853:Cysteine Proteinase Inhibitors; D008024:Ligands; D019151:Peptide Library; D010456:Peptides, Cyclic; D002403:Cathepsins; D003546:Cysteine Endopeptidases; D002401:Cathepsin B; C534281:CTSL protein, human; D056668:Cathepsin L; C534126:CTSH protein, human; D056655:Cathepsin H; D010206:Papain; C534130:CTSK protein, human; D056657:Cathepsin K