title: Interrogation of the Active Sites of Protein Arginine Deiminases (PAD1, -2, and -4) Using Designer Probes.
abstract: Protein arginine deiminases (PADs) are involved in a number of cellular pathways, and they catalyze the transformation of peptidyl arginine residue into a citrulline as part of post-translational modifications. To understand ligand preferences, a group of probe molecules were investigated against PAD1, PAD2, and PAD4. These probe molecules carried a well-known covalent modifier of the catalytic cysteine residue, 2-chloroacetamidine moiety, which was tethered to an α-amino acid via a carbon linker. The chain length for the linker varied from 0 to 4. Time-dependent assays indicated that 2-chloroacetamidine (2CA) with no linker inhibited all PAD enzymes with a similar trend in the second-order rate constants, although with poor affinity. Among the other three probe molecules, compound 3 with a three-carbon linker exhibited the best second-order rate constants for optimal ligand reactivity with the binding site. These analyses provide insights into the relative patterns of covalent inactivation of PAD isozymes and the design of novel inhibitors targeting PAD enzymes as potential therapeutic targets.
authors.affiliation: Center for Molecular Design and Preformulations and Toronto General Research Institute, University Health Network , Toronto, Ontario, M5G 1L7, Canada ; Center for Molecular Design and Preformulations and Toronto General Research Institute, University Health Network , Toronto, Ontario, M5G 1L7, Canada ; Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto , Toronto, Ontario, M5S 3M2, Canada.
authors.forename: Angelica M
authors.initials: AM
authors.lastname: Bello
authors.affiliation: Center for Molecular Design and Preformulations and Toronto General Research Institute, University Health Network , Toronto, Ontario, M5G 1L7, Canada ; Center for Molecular Design and Preformulations and Toronto General Research Institute, University Health Network , Toronto, Ontario, M5G 1L7, Canada.
authors.forename: Ewa
authors.initials: E
authors.lastname: Wasilewski
authors.affiliation: Center for Molecular Design and Preformulations and Toronto General Research Institute, University Health Network , Toronto, Ontario, M5G 1L7, Canada ; Center for Molecular Design and Preformulations and Toronto General Research Institute, University Health Network , Toronto, Ontario, M5G 1L7, Canada ; Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto , Toronto, Ontario, M5S 3M2, Canada.
authors.forename: Lianhu
authors.initials: L
authors.lastname: Wei
authors.affiliation: Department of Structural Biology and Biochemistry, The Hospital for Sick Children , Toronto, Ontario, M5G 1X8, Canada.
authors.forename: Mario A
authors.initials: MA
authors.lastname: Moscarello
authors.affiliation: Center for Molecular Design and Preformulations and Toronto General Research Institute, University Health Network , Toronto, Ontario, M5G 1L7, Canada ; Center for Molecular Design and Preformulations and Toronto General Research Institute, University Health Network , Toronto, Ontario, M5G 1L7, Canada ; Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto , Toronto, Ontario, M5S 3M2, Canada.
authors.forename: Lakshmi P
authors.initials: LP
authors.lastname: Kotra
keywords: PAD; chemical probes; inhibitor design; protein arginine deiminase