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Probing Local Structural Fluctuations In Myoglobin By Size-Dependent Thiol-Disulfide Exchange, Margaret M. Stratton, S N. Loh, T A. Cutler, J H. Ha

Biochemistry & Molecular Biology Department Faculty Publication Series

All proteins undergo local structural fluctuations (LSFs) or breathing motions. These motions are likely to be important for function but are poorly understood. LSFs were initially defined by amide hydrogen exchange (HX) experiments as opening events, which expose a small number of backbone amides to (1)H/(2)H exchange, but whose exchange rates are independent of denaturant concentration. Here, we use size-dependent thiol-disulfide exchange (SX) to characterize LSFs in single cysteine-containing variants of myoglobin (Mb). SX complements HX by providing information on motions that disrupt side chain packing interactions. Most importantly, probe reagents of different sizes and chemical properties can be used …