Folding and stability of endoglucanase III, a single-domain cellulase from Trichoderma reesei.


The reversible folding of an endoglucanase (EGIII) from the filamentous fungus Trichoderma reesei was investigated by activity, tryptophan fluorescence, and peptide CD measurements. Equilibrium stability was determined by urea denaturation at various pH and temperature values. Unfolding and refolding rates were measured over a range of urea concentrations. The data from the equilibrium and kinetic studies fit a simple two-state model, except at lower urea concentrations, where the folding kinetics indicate a transient intermediate. Unfolding is very slow, with a half-life of about 2 h in 8 M urea at pH 5.5 and 25 degrees C. Comparison of the urea dependence of the folding kinetics and equilibrium indicates the protein undergoes 93% of its total change in solvent exposure on going from the unfolded state to the transition state. Thus, the transition state is quite compact. The presence of dithiothreitol destabilized the protein by 7 kcal/mol, indicating the presence of an unusually strong disulfide linkage between the two cysteines in the molecule. Protein stability is dramatically reduced at alkaline pH values; this can be attributed to a titratable shift (pKa = 7.8) in the slope of the urea dependence of unfolding. Study holds ProTherm entries: 4840, 4841 Extra Details: two-state model; transient intermediate; folding kinetics;,solvent exposure; disulfide linkage; cysteines

Submission Details


Submitter: Connie Wang

Submission Date: April 24, 2018, 8:27 p.m.

Version: 1

Publication Details
Arunachalam U;Kellis JT,Biochemistry (1996) Folding and stability of endoglucanase III, a single-domain cellulase from Trichoderma reesei. PMID:8784193
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
99.7 Endoglucanase EG-1 P07981 GUN1_HYPJE
99.7 Endoglucanase EG-1 A0A024SNB7 GUN1_HYPJR
95.4 Endoglucanase EG-1 Q12714 GUN1_TRILO
100.0 Endoglucanase EG-II P07982 GUN2_HYPJE
99.3 Endoglucanase EG-II A0A024SH20 GUN2_HYPJR