High thermal stability of 3-isopropylmalate dehydrogenase from Thermus thermophilus resulting from low DeltaC(p) of unfolding.


To characterize the thermal stability of 3-isopropylmalate dehydrogenase (IPMDH) from an extreme thermophile, Thermus thermophilus, urea-induced unfolding of the enzyme and of its mesophilic counterpart from Escherichia coli was investigated at various temperatures. The unfolding curves were analyzed with a three-state model for E.coli IPMDH and with a two-state model for T.thermophilus IPMDH, to obtain the free energy change DeltaG degrees of each unfolding process. Other thermodynamic parameters, enthalpy change DeltaH, entropy change DeltaS and heat capacity change DeltaC(p), were derived from the temperature dependence of DeltaG degrees. The main feature of the thermophilic enzyme was its lower dependence of DeltaG degrees on temperature resulting from a low DeltaC(p). The thermophilic IPMDH had a significantly lower DeltaC(p), 1.73 kcal/mol.K, than that of E.coli IPMDH (20.7 kcal/mol.K). The low DeltaC(p) of T.thermophilus IPMDH could not be predicted from its change in solvent-accessible surface area DeltaASA. The results suggested that there is a large structural difference between the unfolded state of T.thermophilus and that of E.coli IPMDH. Another responsible factor for the higher thermal stability of T.thermophilus IPMDH was the increase in the most stable temperature T(s). The DeltaG degrees maximum of T.thermophilus IPMDH was much smaller than that of E.coli IPMDH. The present results clearly demonstrated that a higher melting temperature T(m) is not necessarily accompanied by a higher DeltaG degrees maximum. Study holds ProTherm entries: 12762, 12763, 12764 Extra Details: Tween 20(0.01%) was added in the experiment. N - I heat capacity change; 3-isopropylmalate dehydrogenase; protein unfolding;,thermal stability; thermophilic protein

Submission Details

ID: 5CTy8sU83

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:44 p.m.

Version: 1

Publication Details
Motono C;Oshima T;Yamagishi A,Protein Eng. (2001) High thermal stability of 3-isopropylmalate dehydrogenase from Thermus thermophilus resulting from low DeltaC(p) of unfolding. PMID:11809926
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 3-isopropylmalate dehydrogenase P30125 LEU3_ECOLI
99.7 3-isopropylmalate dehydrogenase Q326G2 LEU3_SHIBS
99.7 3-isopropylmalate dehydrogenase Q1RGC4 LEU3_ECOUT
99.4 3-isopropylmalate dehydrogenase Q8X9Z9 LEU3_ECO57
99.4 3-isopropylmalate dehydrogenase Q3Z5T7 LEU3_SHISS
99.4 3-isopropylmalate dehydrogenase Q8FL76 LEU3_ECOL6
99.2 3-isopropylmalate dehydrogenase Q83SP1 LEU3_SHIFL
99.2 3-isopropylmalate dehydrogenase Q32K21 LEU3_SHIDS
94.5 3-isopropylmalate dehydrogenase Q57TE7 LEU3_SALCH
94.5 3-isopropylmalate dehydrogenase P37412 LEU3_SALTY
94.2 3-isopropylmalate dehydrogenase Q5PDG2 LEU3_SALPA
93.7 3-isopropylmalate dehydrogenase Q8Z9I1 LEU3_SALTI
100.0 3-isopropylmalate dehydrogenase Q5SIY4 LEU3_THET8
99.4 3-isopropylmalate dehydrogenase P61494 LEU3_THET2
100.0 3-isopropylmalate dehydrogenase P61495 LEU3_THETH
91.9 3-isopropylmalate dehydrogenase P24098 LEU3_THEAQ