Linked Life Data

16245939

Source:http://linkedlifedata.com/resource/pubmed/id/16245939

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
43
pubmed:dateCreated
2005-10-25
pubmed:abstractText
Halorhodopsin from Natronomonas pharaonis is a light-driven chloride pump which transports a chloride anion across the plasma membrane following light absorption by a retinal chromophore which initiates a photocycle. It was shown that the chloride anion bound in the vicinity of retinal PSB can be replaced by several inorganic anions, including azide which converts the chloride pump into a proton pump and induces formation of an M-like intermediate detected in the bR photocycle but not in native halorhodopsin. Here we have studied the possibility of replacing the chloride anion with organic anions and have followed the photocycle under several conditions. It is revealed that the chloride can be replaced with a formate anion but not with larger organic anions such as acetate. Flash photolysis experiments detected in the formate pigment an M-like intermediate characterized by a lifetime much longer than that of the O intermediate. The lifetime of the M-like intermediate depends on the pH, and its decay is significantly accelerated at low pH. The decay rate exhibited a titration-like curve, suggesting that the protonation of a protein residue controls the rate of M decay. Similar behavior was detected in N. pharaonis pigments in which the chloride anion was replaced with NO(2)(-) and OCN(-) anions. It is suggested that the formation of the M-like intermediate indicates branching pathways from the L intermediate or basic heterogeneity in the original pigment.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Nov
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
1
pubmed:volume
44
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
14231-7
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2005
pubmed:articleTitle
Effect of anions on the photocycle of halorhodopsin. Substitution of chloride with formate anion.
pubmed:affiliation
Department of Organic Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't