Experimental strategies to quantify biomolecular affinity and kinetics: the SARS‑CoV‑2 spike–ACE2 interaction as a benchmark

Transient formation of macromolecular complexes is ubiquitous in biology. This review compares ensemble and single-molecule methods quantifying affinity and kinetics of the underlying non-covalent interactions. Their application is illustrated by comparing the outcome of almost 60 studies, which report >1000 binding properties of SARS-CoV-2’s spike protein interacting with its receptor angiotensin-converting enzyme 2. Similarities and differences are discussed with respect to the method employed and aspect of the interaction probed.