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Different pressure-temperature behavior of the structured and unstructured regions of titin.
MedLine Citation:
PMID:  23063534     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Contrary to the classical view, according to which all proteins adopt a specific folded conformation necessary for their function, intrinsically unstructured proteins (IUPs) display random-coil-like conformation under physiological conditions. We compared the structured and unstructured domains from titin, a giant protein responsible for striated-muscle elasticity. A 171-residue-long fragment (polyE) of the disordered PEVK domain, and an Ig domain (I27) with ordered structure were investigated. FTIR (Fourier transform infrared) and fluorescence spectroscopy combined with a diamond anvil cell were used for investigation of the secondary structures under wide range of pressure and temperature. PolyE preserves its disordered characteristics across the entire range of investigated pressure (0-16kbar), temperature (0-100°C), pD (3-10.5) and different solvent conditions. The detailed temperature-pressure phase diagram of titin I27 was determined. At 30°C, increasing pressure unfolds titin I27 in one step at 10.5kbar. Increasing temperature at atmospheric pressure results in two transitions. At 50°C the secondary structure is loosened and the protein transforms into a molten-globule state. At 65°C the protein completely unfolds. Unfolding is followed by aggregation at ambient pressure. Moderate pressures (>2kbar), however, can prevent the protein from aggregation. Our experiments in wide range of physical parameters revealed four different structures for I27, while the unstructured character of the PEVK fragment is insensitive to these parameters.
Authors:
Judit Somkuti; Zsolt Mártonfalvi; Miklós S Z Kellermayer; László Smeller
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-10-10
Journal Detail:
Title:  Biochimica et biophysica acta     Volume:  -     ISSN:  0006-3002     ISO Abbreviation:  Biochim. Biophys. Acta     Publication Date:  2012 Oct 
Date Detail:
Created Date:  2012-10-15     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0217513     Medline TA:  Biochim Biophys Acta     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2012. Published by Elsevier B.V.
Affiliation:
Department of Biophysics and Radiation Biology, Semmelweis University, 1094 Tuzolto utca 37-47, Budapest, Hungary.
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