P22 Arc repressor: folding kinetics of a single-domain, dimeric protein.


The rate constants for refolding and unfolding of the P22 Arc repressor dimer have been determined by stop-flow fluorescence experiments. Under most conditions, refolding is described well as a two-state reaction with a bimolecular rate-limiting step (kf approximately 10(7) M-1 s-1). A unimolecular step appears to become co-rate limiting at high protein concentrations. The urea dependence of the refolding reaction suggests that about 75% of the total burial of hydrophobic surface occurs between the unfolded state and the transition state for folding. Hydrophobic interactions are also evidenced by the temperature dependence of the refolding reaction; the rate increases with temperature and Arrhenius plots are curved, as expected for a reaction that proceeds with a significant heat capacity change. The refolding of Arc also proceeds more rapidly as the salt concentration is raised, presumably because repulsive interactions between monomers are screened. At a protein concentration of 10 microM, the apparent rate constant for refolding of the Arc dimer is approximately 100 s-1, as fast as the refolding of many monomeric proteins. The rate constant for unfolding is approximately 0.1 s-1, corresponding to a half-life of less than 10 s for the folded Arc dimer. This rate of unfolding is very fast in comparison to that of other characterized proteins and implies that a free Arc molecule must unfold and refold hundreds of times per generation in the cell. Study holds ProTherm entries: 4648, 4649 Extra Details: additive : EDTA(0.2 mM), rate constants; two-state reaction; hydrophobic surface;,bimolecular rate-limiting step; Arrhenius plots

Submission Details


Submitter: Connie Wang

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

Version: 1

Publication Details
Milla ME;Sauer RT,Biochemistry (1994) P22 Arc repressor: folding kinetics of a single-domain, dimeric protein. PMID:8110744
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 Transcriptional repressor arc P03050 RARC_BPP22