Thermodynamics of barnase unfolding.


Abstract

The thermodynamics of barnase denaturation has been studied calorimetrically over a broad range of temperature and pH. It is shown that in acidic solutions the heat denaturation of barnase is well approximated by a 2-state transition. The heat denaturation of barnase proceeds with a significant increase of heat capacity, which determines the temperature dependencies of the enthalpy and entropy of its denaturation. The partial specific heat capacity of denatured barnase is very close to that expected for the completely unfolded protein. The specific denaturation enthalpy value extrapolated to 130 degrees C is also close to the value expected for the full unfolding. Therefore, the calorimetrically determined thermodynamic characteristics of barnase denaturation can be considered as characteristics of its complete unfolding and can be correlated with structural features--the number of hydrogen bonds, extent of van der Waals contacts, and the surface areas of polar and nonpolar groups. Using this information and thermodynamic information on transfer of protein groups into water, the contribution of various factors to the stabilization of the native structure of barnase has been estimated. The main contributors to the stabilization of the native state of barnase appear to be intramolecular hydrogen bonds. The contributions of van der Waals interactions between nonpolar groups and those of hydration effects of these groups are not as large if considered separately, but the combination of these 2 factors, known as hydrophobic interactions, is of the same order of magnitude as the contribution of hydrogen bonding. Study holds ProTherm entries: 3024 Extra Details: hydrogen bonding; hydrophobic interactions; barnase;,scanning microcalorimetry

Submission Details

ID: 4Pj2fo5Y3

Submitter: Connie Wang

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

Version: 1

Publication Details
Griko YV;Makhatadze GI;Privalov PL;Hartley RW,Protein Sci. (1994) Thermodynamics of barnase unfolding. PMID:8003984
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 PDB Entries

Structure ID Release Date Resolution Structure Title
1B2U 1998-12-01T00:00:00+0000 2.1 STRUCTURAL RESPONSE TO MUTATION AT A PROTEIN-PROTEIN INTERFACE
1B2S 1998-11-30T00:00:00+0000 1.82 STRUCTURAL RESPONSE TO MUTATION AT A PROTEIN-PROTEIN INTERFACE
1B2Z 1998-12-03T00:00:00+0000 2.03 DELETION OF A BURIED SALT BRIDGE IN BARNASE
1B2X 1998-12-03T00:00:00+0000 1.8 BARNASE WILDTYPE STRUCTURE AT PH 7.5 FROM A CRYO_COOLED CRYSTAL AT 100K
3KCH 2009-10-21T00:00:00+0000 1.94 Baranase crosslinked by glutaraldehyde
1B21 1998-12-03T00:00:00+0000 2.0 DELETION OF A BURIED SALT BRIDGE IN BARNASE
1B20 1998-12-03T00:00:00+0000 1.7 DELETION OF A BURIED SALT-BRIDGE IN BARNASE
1A2P 1998-01-07T00:00:00+0000 1.5 BARNASE WILDTYPE STRUCTURE AT 1.5 ANGSTROMS RESOLUTION
1FW7 2000-09-22T00:00:00+0000 0 NMR STRUCTURE OF 15N-LABELED BARNASE
1BGS 1993-11-02T00:00:00+0000 2.6 RECOGNITION BETWEEN A BACTERIAL RIBONUCLEASE, BARNASE, AND ITS NATURAL INHIBITOR, BARSTAR

Relevant UniProtKB Entries

Percent Identity Matching Chains Protein Accession Entry Name
97.3 Ribonuclease P35078 RN_BACCI
100.0 Ribonuclease P00648 RNBR_BACAM