Quantifying the kinetic stability of hyperstable proteins via time-dependent SDS trapping.

Globular proteins are usually in equilibrium with unfolded conformations, whereas kinetically stable proteins (KSPs) are conformationally trapped by their high unfolding transition state energy. Kinetic stability (KS) could allow proteins to maintain their activity under harsh conditions, increase a protein's half-life, or protect against misfolding-aggregation. Here we show the development of a simple method for quantifying a protein's KS that involves incubating a protein in SDS at high temperature as a function of time, running the unheated samples on SDS-PAGE, and quantifying the bands to determine the time-dependent loss of a protein's SDS resistance.