12058039

Source:http://linkedlifedata.com/resource/pubmed/id/12058039

Download in:

Switch to

Custom View

Named Graph Language Inference

Statements in which the resource exists as a subject.
Predicate	Object
rdf:type	pubmed:Citation
lifeskim:mentions	umls-concept:C0004654, umls-concept:C0023779, umls-concept:C0033625, umls-concept:C0035820, umls-concept:C0037812, umls-concept:C0205360, umls-concept:C0302891, umls-concept:C0678594, umls-concept:C2603343
pubmed:issue	33
pubmed:dateCreated	2002-8-12
pubmed:abstractText	We report the effect of partial delipidation and monomerization on the protein conformational changes of bacteriorhodopsin (bR) as a function of temperature. Removal of up to 75% of the lipids is known to have the lattice structure of the purple membrane, albeit as a smaller unit cell, whereas treatment by Triton monomerizes bR into micelles. The effects of these modifications on the protein secondary structure is analyzed by monitoring the protein amide I and amide II bands in the Fourier transform-infrared (FT-IR) spectra. It is found that removal of the first 75% of the lipids has only a slight effect on the secondary structure at physiological temperature, whereas monomerizing bR into micelles alters the secondary structure considerably. Upon heating, the bR monomer is found to have a very low thermal stability compared with the native bR with its melting point reduced from 97 to 65 degrees C, and the pre-melting transition in which the protein changes conformation in native bR at 80 degrees C could not be observed. Also, the N[bond]H to N[bond]D exchange of the amide II band is effectively complete at room temperature, suggesting that there are no hydrophobic regions that are protected from the aqueous medium, possibly explaining the low thermal stability of the monomer. On the other hand, 75% delipidated bR has its melting temperature close to that of the native bR and does have a pre-melting transition, although the pre-melting transition occurs at significantly higher temperature than that of the native bR (91 degrees C compared with 80 degrees C) and is still reversible. Furthermore, we have also observed that the reversibility of this pre-melting transition of both native and partially delipidated bR is time-dependent and becomes irreversible upon holding at 91 degrees C between 10 and 30 min. These results are discussed in terms of the lipid and lattice contribution to the protein thermal stability of native bR.
pubmed:language	eng
pubmed:journal	http://linkedlifedata.com/resource/pubmed/journal/2985121R
pubmed:citationSubset	IM
pubmed:chemical	http://linkedlifedata.com/resource/pubmed/chemical/Bacteriorhodopsins, http://linkedlifedata.com/resource/pubmed/chemical/Lipids
pubmed:status	MEDLINE
pubmed:month	Aug
pubmed:issn	0021-9258
pubmed:author	pubmed-author:El-SayedMostafa AMA, pubmed-author:HeyesColin DCD
pubmed:issnType	Print
pubmed:day	16
pubmed:volume	277
pubmed:owner	NLM
pubmed:authorsComplete	Y
pubmed:pagination	29437-43
pubmed:dateRevised	2006-11-15
pubmed:meshHeading	pubmed-meshheading:12058039-Bacteriorhodopsins, pubmed-meshheading:12058039-Lipids, pubmed-meshheading:12058039-Protein Conformation, pubmed-meshheading:12058039-Spectroscopy, Fourier Transform Infrared, pubmed-meshheading:12058039-Temperature
pubmed:year	2002
pubmed:articleTitle	The role of the native lipids and lattice structure in bacteriorhodopsin protein conformation and stability as studied by temperature-dependent Fourier transform-infrared spectroscopy.
pubmed:affiliation	Laser Dynamics Laboratory, School of Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, USA.
pubmed:publicationType	Journal Article, Research Support, U.S. Gov't, Non-P.H.S.