Phosphate Chemical Probes Designed for Location Specific Inhibition of Intracellular Carbonic Anhydrases

Chemical
probes are small molecules designed to bind to a specific
protein and disrupt the proteins function. Although many inhibitors
are reported for human carbonic anhydrase (CA) enzymes, few may be
considered useful as chemical probes as they exhibit broad action
against the 12 catalytically active CA isozymes. In addition, most
do not possess an appropriate physicochemical profile to discriminate
intracellular CA activity from either global or extracellular CA activity.
We report herein the synthesis of three monophosphate CA proinhibitors (compounds 2, 3, and 5) that are derived from cyclosaligenyl (cycloSal)
phosphate and S-acyl-2-thioethyl (SATE) phosphate
as protecting groups. The proinhibitors are designed
as neutral, membrane-permeable compounds that once inside the cell
may be hydrolyzed by pH-driven or enzymatic-driven mechanisms to release
a negatively charged monophosphate. The resulting monophosphate compound
is trapped intracellularly and available for locality specific inhibition
of intracellular CAs.