We have recently reported on the use of aryl-fluorosulfates
in
designing water- and plasma-stable agents that covalently target Lys,
Tyr, or His residues in the BIR3 domain of the inhibitor of the apoptosis
protein (IAP) family. Here, we report further structural, cellular,
and pharmacological characterizations of this agent, including the
high-resolution structure of the complex between the Lys-covalent
agent and its target, the BIR3 domain of X-linked IAP (XIAP). We also
compared the cellular efficacy of the agent in two-dimensional (2D)
and three-dimensional (3D) cell cultures, side by side with the clinical
candidate reversible IAP inhibitor LCL161. Finally,in vivopharmacokinetic studies indicated that the agent was long-lived
and orally bioavailable. Collectively our data further corroborate
that aryl-fluorosulfates, when incorporated correctly in a ligand,
can result in Lys-covalent agents with pharmacodynamic and pharmacokinetic
properties that warrant their use in the design of pharmacological
probes or even therapeutics.