Linked Life Data

11107860

Source:http://linkedlifedata.com/resource/pubmed/id/11107860

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
5
pubmed:dateCreated
2001-2-15
pubmed:abstractText
The proton channels of the bacteriorhodopsin (BR) proton pump contain bound water molecules. The channels connect the purple membrane surfaces with the protonated retinal Schiff base at the membrane center. Films of purple membrane equilibrated at low relative humidity display a shift of the 570 nm retinal absorbance maximum to 528 nm, with most of the change occurring below 15% relative humidity. Purple membrane films were dehydrated to defined humidities between about 50 and 4.5% and examined by Fourier transform infrared difference spectroscopy. In spectra of dehydrated-minus-hydrated purple membrane, troughs are observed at 3645 and 3550 cm-1, and peaks are observed at 3665 and 3500 cm-1. We attribute these changes to water dissociation from the proton uptake channel and the resulting changes in hydrogen bonding of water that remains bound. Also, in the carboxylic acid spectral region, a trough was observed at 1742 cm-1 and a peak at 1737 cm-1. The magnitude of the trough to peak difference between 1737 and 1742 cm-1 correlates linearly with the extent of the 528 nm pigment. This suggests that a carboxylic acid group or groups is undergoing a change in environment as a result of dehydration, and that this change is linked to the appearance of the 528 nm pigment. Dehydration difference spectra with BR mutants D96N and D115N show that the 1737-1742 cm-1 change is due to Asp 96 and Asp 115. A possible mechanism is suggested that links dissociation of water in the proton uptake channel to the environmental change at the Schiff base site.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Nov
pubmed:issn
0031-8655
pubmed:author
pubmed:issnType
Print
pubmed:volume
72
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
714-8
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
2000
pubmed:articleTitle
Water and carboxyl group environments in the dehydration blueshift of bacteriorhodopsin.
pubmed:affiliation
Division of Life Sciences, University of Texas at San Antonio 78249, USA. rrenthal@utsa.edu
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.