Effect of an intersubunit disulfide bond on the stability of Streptomyces subtilisin inhibitor.
The effect of an engineered disulfide bond between two identical subunits of a dimeric protein, Streptomyces subtilisin inhibitor, on the stability of the protein was studied by differential scanning calorimetry. The introduction of the linkage caused a large stabilization without changing the cooperativity of unfolding, with the denaturation temperature of a 2 mg/mL solution being increased by 14.3 degrees C to 95.0 degrees C at pH 9.5 and by 16.4 degrees C to 63.0 degrees C at pH 3.0. The stabilization was caused by a loss of denaturational entropy, i.e., -40 and -98 cal K-1 mol-1 at pH 3.0 and 9.5, respectively, which more than compensated for the loss in the denaturational enthalpy.
Tamura
A
A
Department of Chemistry, Yale University, New Haven, Connecticut 06520.
Kojima
S
S
Miura
K
K
Sturtevant
J M
JM
D001426:Bacterial Proteins / Q000737:chemistry*; D002152:Calorimetry, Differential Scanning; D017931:DNA Primers / Q000737:chemistry; D004220:Disulfides; D006863:Hydrogen-Ion Concentration; D016297:Mutagenesis, Site-Directed; D011489:Protein Denaturation; D013302:Streptomyces / Q000201:enzymology*; D013329:Structure-Activity Relationship; D013381:Subtilisins / Q000037:antagonists & inhibitors*; D013816:Thermodynamics
D001426:Bacterial Proteins; D017931:DNA Primers; D004220:Disulfides; C018150:subtilisin inhibitor protein, Streptomyces; D013381:Subtilisins