conformationally isoformic thermophilic protein with high kinetic unfolding barriers

The basis for the stability of thermophilic proteins is of fundamental interest for extremophile biology. We investigated the folding and unfolding processes of the homotetrameric Thermoanaerobacter brockii alcohol dehydrogenase (TBADH). TBADH subunits were 4.8 kcal/mol less stable towards guanidini...

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Bibliographic Details
Published in:Cellular and molecular life sciences : CMLS 2008-03, Vol.65 (5), p.827-839
Main Authors: Mishra, R, Olofsson, L, Karlsson, M, Carlsson, U, Nicholls, I. A, Hammarström, P
Format: Article
Language:English
Subjects:
Alcohol Dehydrogenase - chemistry
Alcohol Dehydrogenase - isolation & purification
Alcohol Dehydrogenase - metabolism
Biochemistry
Biokemi
Biomedical and Life Sciences
Biomedicine
Biotechnology
Bioteknik
Cell Biology
Chemical denaturant
conformational isoforms
Cross-Linking Reagents - pharmacology
Dimerization
Guanidine - pharmacology
ionic interactions
Isoenzymes
kinetic stability
Kinetics
Life Sciences
Models, Chemical
Models, Molecular
NATURAL SCIENCES
NATURVETENSKAP
Organic Chemistry
Organisk kemi
Prions
Protein Conformation
Protein Folding
Protein Renaturation
protein unfolding
Proteins
Research Article
Saccharomyces cerevisiae
Thermoanaerobacter - enzymology
Thermoanaerobacter - growth & development
Thermoanaerobacter brockii alcohol dehydrogenase
Thermodynamics
Urea
Urea - pharmacology
Yeasts
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Summary:The basis for the stability of thermophilic proteins is of fundamental interest for extremophile biology. We investigated the folding and unfolding processes of the homotetrameric Thermoanaerobacter brockii alcohol dehydrogenase (TBADH). TBADH subunits were 4.8 kcal/mol less stable towards guanidinium chloride (GdmCl) unfolding compared to urea, indicating ionic modulation of TBADH stability. Strongly denaturing conditions promoted mono-exponential unfolding kinetics with linear dependence on denaturant concentration. Here TBADH unfolded >40-fold slower when extrapolated from urea as compared to GdmCl unfolding. A marked unfolding hysteresis was shown when comparing refolding and unfolding in urea. An unusual biphasic unfolding trajectory with an exceptionally slow phase at intermediate concentrations of GdmCl and urea was also observed. We advocate that TBADH forms two distinctly different tetrameric isoforms, and likely an ensemble of native states. This unusual supramolecular folding behavior has been shown responsible for formation of amyloidotic yeast prion strains and can have functional importance for TBADH.
ISSN:1420-682X
1420-9071
1420-9071
DOI:10.1007/s00018-008-7517-4