A two-state conformational transition of the extracellular ribonuclease of Bacillus amyloliquefaciens (barnase) induced by sodium dodecyl sulfate.

Barnase, the extracellular ribonuclease of Bacillus amyloliquefaciens, is shown to undergo a reversible two-state conformational transition at 0.65 mM sodium dodecyl sulfate (SDS) AAT 37 DEGREES. The prinicipal evidence is based on the equivalence of two independent values of the SDS-barnase binding ratio; about 14 mol of SDS/mol of barnase. Both were derived from fluorometric titration data, one being based on simple conservation of SDS and the other on the use of Wyman's theory of linked functions. No SDS is bound to barnase at SDS concentrations below the transition region.