Kinetic analysis of folding and unfolding the 56 amino acid IgG-binding domain of streptococcal protein G.


Abstract

The 56 amino acid B domain of protein G (GB) is a stable globular folding unit with no disulfide cross-links. The physical properties of GB offer extraordinary flexibility for evaluating the energetics of the folding reaction. The protein is monomeric and very soluble in both folded and unfolded forms. The folding reaction has been previously examined by differential scanning calorimetry (Alexander et al., 1992) and found to exhibit two-state unfolding behavior over a wide pH range with an unfolding transition near 90 degrees C (GB1) at neutral pH. Here, the kinetics of folding and unfolding two naturally occurring versions of GB have been measured using stopped-flow mixing methods and analyzed according to transition-state theory. GB contains no prolines, and the kinetics of folding and unfolding can be fit to a single, first-order rate constant over the temperature range of 5-35 degrees C. The major thermodynamic changes going from the unfolded state to the transition state are (1) a large decrease in heat capacity (delta Cp), indicating that the transition state is compact and solvent inaccessible relative to the unfolded state; (2) a large loss of entropy; and (3) a small increase in enthalpy. The most surprising feature of the folding of GB compared to that of previously studied proteins is that its folding approximates a rapid diffusion controlled process with little increase in enthalpy going from the unfolded to the transition state. Study holds ProTherm entries: 5343, 5344, 5345, 5346 Extra Details: globular folding unit; flexibility; transition-state theory;,entropy

Submission Details

ID: 8o2uKuXw3

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:29 p.m.

Version: 1

Publication Details
Alexander P;Orban J;Bryan P,Biochemistry (1992) Kinetic analysis of folding and unfolding the 56 amino acid IgG-binding domain of streptococcal protein G. PMID:1510916
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
1EM7 2000-03-16T00:00:00+0000 2.0 HELIX VARIANT OF THE B1 DOMAIN FROM STREPTOCOCCAL PROTEIN G
1GB1 1991-05-15T00:00:00+0000 0 A NOVEL, HIGHLY STABLE FOLD OF THE IMMUNOGLOBULIN BINDING DOMAIN OF STREPTOCOCCAL PROTEIN G
1IGC 1994-08-05T00:00:00+0000 2.6 IGG1 FAB FRAGMENT (MOPC21) COMPLEX WITH DOMAIN III OF PROTEIN G FROM STREPTOCOCCUS
1IGD 1994-08-05T00:00:00+0000 1.1 THE THIRD IGG-BINDING DOMAIN FROM STREPTOCOCCAL PROTEIN G: AN ANALYSIS BY X-RAY CRYSTALLOGRAPHY OF THE STRUCTURE ALONE AND IN A COMPLEX WITH FAB
1LE3 2002-04-09T00:00:00+0000 0 NMR Structure of Tryptophan Zipper 4: A Stable Beta-Hairpin Peptide Based on the C-terminal Hairpin of the B1 Domain of Protein G
1MPE 2002-09-12T00:00:00+0000 0 Ensemble of 20 structures of the tetrameric mutant of the B1 domain of streptococcal protein G
1MVK 2002-09-25T00:00:00+0000 2.5 X-ray structure of the tetrameric mutant of the B1 domain of streptococcal protein G
1PGA 1993-11-23T00:00:00+0000 2.07 TWO CRYSTAL STRUCTURES OF THE B1 IMMUNOGLOBULIN-BINDING DOMAIN OF STREPTOCOCCAL PROTEIN G AND COMPARISON WITH NMR
1PGB 1993-11-23T00:00:00+0000 1.92 TWO CRYSTAL STRUCTURES OF THE B1 IMMUNOGLOBULIN-BINDING DOMAIN OF STREPTOCCOCAL PROTEIN G AND COMPARISON WITH NMR
1PGX 1992-04-03T00:00:00+0000 1.66 THE 1.66 ANGSTROMS X-RAY STRUCTURE OF THE B2 IMMUNOGLOBULIN-BINDING DOMAIN OF STREPTOCOCCAL PROTEIN G AND COMPARISON TO THE NMR STRUCTURE OF THE B1 DOMAIN

Relevant UniProtKB Entries

Percent Identity Matching Chains Protein Accession Entry Name
100.0 Immunoglobulin G-binding protein G P19909 SPG2_STRSG
100.0 Immunoglobulin G-binding protein G P06654 SPG1_STRSG