Protein engineering of subtilisin BPN': enhanced stabilization through the introduction of two cysteines to form a disulfide bond.


Introduction of a disulfide bond by site-directed mutagenesis was found to enhance the stability of subtilisin BPN' (EC under a variety of conditions. The location of the new disulfide bond was selected with the aid of a computer program, which scored various sites according to the amount of distortion that an introduced disulfide linkage would create in a 1.3-A X-ray model of native subtilisin BPN'. Of the several amino acid pairs identified by this program as suitable candidates, Thr-22 and Ser-87 were selected by using the additional requirement that the individual cysteine substitutions occur at positions that exhibit some degree of variability in related subtilisin amino acid sequences. A subtilisin variant containing cysteine residues at positions 22 and 87 was created by site-directed mutagenesis and was shown to have an activity essentially equivalent to that of the wild-type enzyme. Differential scanning calorimetry experiments demonstrated the variant protein to have a melting temperature 3.1 degrees C higher than that of the wild-type protein and 5.8 degrees C higher than that of the reduced form (-SH HS-) of the variant protein. Kinetic experiments performed under a variety of conditions, including 8 M urea, showed that the Cys-22/Cys-87 disulfide variant undergoes thermal inactivation at half the rate of that of the wild-type enzyme. The increased thermal stability of this disulfide variant is consistent with a decrease in entropy for the unfolded state relative to the unfolded state that contains no cross-link, as would be predicted from the statistical thermodynamics of polymers. Study holds ProTherm entries: 3031, 3032, 3033, 3034 Extra Details: additive : EDTA(10 mM), subtilisin BPN'; disulfide bond; protein engineering;,cysteine; statistical thermodynamics; stabilization

Submission Details


Submitter: Connie Wang

Submission Date: April 24, 2018, 8:20 p.m.

Version: 1

Publication Details
Pantoliano MW;Ladner RC;Bryan PN;Rollence ML;Wood JF;Poulos TL,Biochemistry (1987) Protein engineering of subtilisin BPN': enhanced stabilization through the introduction of two cysteines to form a disulfide bond. PMID:3476160
Additional Information

Structure view and single mutant data analysis

Study data

No weblogo for data of varying length.
Colors: D E R H K S T N Q A V I L M F Y W C G P

Data Distribution

Studies with similar sequences (approximate matches)

Correlation with other assays (exact sequence matches)

Relevant UniProtKB Entries

Percent Identity Matching Chains Protein Accession Entry Name
100.0 Subtilisin BPN' P00782 SUBT_BACAM