Download MendeleyDissection, Optimization, and Structural Analysis of a Covalent Irreversible DDAH1 Inhibitor.
Burstein-Teitelbaum, G., Er, J.A.V., Monzingo, A.F., Tuley, A., Fast, W.(2018) Biochemistry 57: 4574-4582
- PubMed: 29983043
- DOI: https://doi.org/10.1021/acs.biochem.8b00554
- Primary Citation of Related Structures:
6DGE - PubMed Abstract:
Inhibitors of the human enzyme dimethylarginine dimethylaminohydrolase-1 (DDAH1) can control endogenous nitric oxide production. A time-dependent covalent inactivator of DDAH1, N 5 -(1-imino-2-chloroethyl)-l-ornithine ( K I = 1.3 μM, k inact = 0.34 min -1 ), was conceptually dissected into two fragments and each characterized separately: l-norvaline ( K i = 470 μM) and 2-chloroacetamidine ( K I = 310 μM, k inact = 4.0 min -1 ). This analysis suggested that the two fragments were not linked in a manner that allows either to reach full affinity or reactivity, prompting the synthesis and characterization of three analogues: two that mimic the dimethylation status of the substrate, N 5 -(1-imino-2-chloroisopropyl)-l-ornithine ( k inact /K I = 208 M -1 s -1 ) and N 5 -(1-imino-2-chlorisopropyl)-l-lysine ( k inact /K I = 440 M -1 s -1 ), and one that lengthens the linker beyond that found in the substrate, N 5 -(1-imino-2-chloroethyl)-l-lysine (Cl-NIL, K I = 0.19 μM, k inact = 0.22 min -1 ). Cl-NIL is one of the most potent inhibitors reported for DDAH1, inactivates with a second order rate constant (1.9 × 10 4 M -1 s -1 ) larger than the catalytic efficiency of DDAH1 for its endogenous substrate (1.6 × 10 2 M -1 s -1 ), and has a partition ratio of 1 with a >100 000-fold selectivity for DDAH1 over arginase. An activity-based protein-profiling probe is used to show inhibition of DDAH1 within cultured HEK293T cells (IC 50 = 10 μM) with cytotoxicity appearing only at higher concentrations (ED 50 = 118 μM). A 1.91 Å resolution X-ray crystal structure reveals specific interactions made with DDAH1 upon covalent inactivation by Cl-NIL. Dissecting a covalent inactivator and analysis of its constituent fragments proved useful for the design and optimization of this potent and effective DDAH1 inhibitor.
Organizational Affiliation:
Division of Chemical Biology & Medicinal Chemistry, College of Pharmacy , University of Texas , Austin , Texas 78712 , United States.
