The temperature induced unfolding of barstar wild-type of bacillus amyloliquefaciens (90 residues) has been characterized by differential scanning microcalorimetry. The process has been found to be reversible in the pH range from 6.4 to 8.3 in the absence of oxygen. It has been clearly shown by a ratio of delta HvH/delta Hcal near 1 that denaturation follows a two-state mechanism. For comparison, the C82A mutant was also studied. This mutant exhibits similar reversibility, but has a slightly lower transition temperature. The transition enthalpy of barstar wt (303 kJ mol-1) exceeds that of the C82A mutant (276 kJ mol-1) by approximately 10%. The heat capacity changes show a similar difference, delta Cp being 5.3 +/- 1 kJ mol-1 K-1 for the wild-type and 3.6 +/- 1 kJ mol-1 K-1 for the C82A mutant. The extrapolated stability parameters at 25 degrees C are delta G0 = 23.5 +/- 2 kJ mol-1 for barstar wt and delta G0 = 25.5 +/- 2 kJ mol-1 for the C82A mutant. Study holds ProTherm entries: 3226, 3227 Extra Details: additive : EDTA(1 mM) aggregation prevention; barstar wild-type; DSC;,oxidation; thermodynamics
Submitter: Connie Wang
Submission Date: April 24, 2018, 8:21 p.m.
|Number of data points||8|
|Proteins||Barstar ; Barstar|
|Assays/Quantities/Protocols||Experimental Assay: dHcal ; Experimental Assay: Tm ; Experimental Assay: dCp ; Derived Quantity: dTm|
|Libraries||Mutations for sequence KKAVINGEQIRSISDLHQTLKKELALPEYYGENLDALWDCLTGWVEYPLVLEWRQFEQSKQLTENGAESVLQVFREAKAEGCDITIILS|