Circular dichroism studies of barnase and its mutants: characterization of the contribution of aromatic side chains.


Abstract

The circular dichroism spectrum of barnase has been analyzed by examining the spectra of a series of mutants in which every single aromatic residue has been replaced. The spectrum of wild-type barnase is quite atypical for a protein of the alpha + beta class, with very low intensities and a minimum in the far-UV at 231 nm. The minimum at 231 nm is associated with the presence of Trp-94. Many other mutations involving aromatic residues have an effect on the spectral features in the far-UV. The major features in the near-UV spectra arise from essentially additive contributions of the three tryptophan residues Trp-35, Trp-71, and Trp-94. Tyrosine contributions are less prominent, with Tyr-78 and Tyr-97 contributing the most to the CD spectrum. The close charge-aromatic interaction between Trp-94 and His-18, which is important for the fluorescence properties of the protein, contributes little to the CD spectrum, as does the close aromatic-aromatic interaction between Tyr-13 and Tyr-17. However, the observed near-UV spectrum of wild-type barnase could not be simulated by the sum of the contributions of aromatic residues defined by difference spectra of protein variants carrying aromatic residues. Aromatic residues play an important role in determining the circular dichroism spectrum of proteins not only in the near-UV but also in the far-UV region. Study holds ProTherm entries: 4657, 4658 Extra Details: aromatic residue; alpha + beta class;,charge-aromatic interaction; aromatic-aromatic interaction

Submission Details

ID: 2LeqJTwF4

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:26 p.m.

Version: 1

Publication Details
Vuilleumier S;Sancho J;Loewenthal R;Fersht AR,Biochemistry (1993) Circular dichroism studies of barnase and its mutants: characterization of the contribution of aromatic side chains. PMID:8399173
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
1A2P 1998-01-07T00:00:00+0000 1.5 BARNASE WILDTYPE STRUCTURE AT 1.5 ANGSTROMS RESOLUTION
1B20 1998-12-03T00:00:00+0000 1.7 DELETION OF A BURIED SALT-BRIDGE IN BARNASE
1B21 1998-12-03T00:00:00+0000 2.0 DELETION OF A BURIED SALT BRIDGE IN BARNASE
1B27 1998-12-04T00:00:00+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
1B2U 1998-12-01T00:00:00+0000 2.1 STRUCTURAL RESPONSE TO MUTATION AT A PROTEIN-PROTEIN INTERFACE
1B2X 1998-12-03T00:00:00+0000 1.8 BARNASE WILDTYPE STRUCTURE AT PH 7.5 FROM A CRYO_COOLED CRYSTAL AT 100K
1B2Z 1998-12-03T00:00:00+0000 2.03 DELETION OF A BURIED SALT BRIDGE IN BARNASE
1B3S 1998-12-01T00:00:00+0000 2.39 STRUCTURAL RESPONSE TO MUTATION AT A PROTEIN-PROTEIN INTERFACE
1BAN 1993-05-19T00:00:00+0000 2.2 THE CONTRIBUTION OF BURIED HYDROGEN BONDS TO PROTEIN STABILITY: THE CRYSTAL STRUCTURES OF TWO BARNASE MUTANTS

Relevant UniProtKB Entries

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