jm9b01019_si_001.pdf (61.94 kB)
Protein Stability Effects in Aggregate-Based Enzyme Inhibition
journal contribution
posted on 2019-10-17, 18:03 authored by Hayarpi Torosyan, Brian K. ShoichetSmall-molecule aggregates are a leading
cause of artifacts in early
drug discovery, but little is known about their interactions with
proteins, nor why some proteins are more susceptible to inhibition
than others. A possible reason for this apparent selectivity is that
aggregation-based inhibition, as a stoichiometric process, is sensitive
to protein concentration, which varies across assays. Alternatively,
local protein unfolding by aggregates may lead to selectivity since
stability varies among proteins. To deconvolute these effects, we
used differentially stable point mutants of a single protein, TEM-1
β-lactamase. Broadly, destabilized mutants had higher affinities
for and were more potently inhibited by aggregates versus more stable
variants. The addition of the irreversible inhibitor moxalactam destabilized
several mutants, and these typically bound tighter to a colloidal
particle, while the only mutant it stabilized bound weaker. These
results suggest that less-stable enzymes are more easily sequestered
and inhibited by colloidal aggregates.