Equilibrium folding studies of tetrameric R67 dihydrofolate reductase.


R67 dihydrofolate reductase (DHFR) is an R-plasmid encoded enzyme that confers resistance to the antibacterial drug trimethoprim. This enzyme is not homologous in sequence or structure to chromosomal DHFRs. Equilibrium folding of tetrameric R67 DHFR was studied and found to be fully reversible. Formation of an inactive intermediate was assayed by loss of enzyme activity. Denaturation of the intermediate was monitored by concurrent changes in fluorescence and circular dichroism signals. Both transitions are protein concentration dependent. A simple model fitting these data is tetramer<==>2 dimers<==>4 unfolded monomers. No evidence for folded monomer was found. Global fitting of all the folding data yielded a delta GH2O of -9.63 kcal/mol for the initial transition and a delta GH2O of -12.35 kcal/mol for the second transition. In addition, thermal unfolding of tetrameric R67 DHFR was found to be reversible A folding intermediate also occurred during thermal unfolding as evidenced by the asymmetric endotherms and a delta Hcalorimetric/delta H(van't Hoff) ratio of 2.1. Study holds ProTherm entries: 4429, 4430, 4431 Extra Details: tetrameric R67 DHFR; enzyme activity; folding intermediate;,asymmetric endotherms

Submission Details

ID: uQVVzmL5

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:25 p.m.

Version: 1

Publication Details
Zhuang P;Eisenstein E;Howell EE,Biochemistry (1994) Equilibrium folding studies of tetrameric R67 dihydrofolate reductase. PMID:8155640
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 Dihydrofolate reductase type 2 P00383 DYR21_ECOLX