Linked Life Data

8931558

Source:http://linkedlifedata.com/resource/pubmed/id/8931558

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
46
pubmed:dateCreated
1997-1-7
pubmed:abstractText
The photochemical reactions of iodopsin at low temperatures were investigated by a combination of absorption spectroscopy and chromophore extraction to show the formation of isomeric photoproducts other than the all-trans intermediates. We first confirmed that the chromophore in iodopsin is an 11-cis-retinal. Next, iodopsin samples were irradiated with light of different wavelengths at selected temperatures ranging from -190 to 0 degrees C, and their retinylidene chromophores were extracted as oximes after warming the sample to 0 degree C. The isomeric composition of the extracted chromophores was analyzed by high-performance liquid chromatography. It was confirmed that bathoiodopsin produced at -190 degrees C has an all-trans chromophore, but a considerable amount of its chromophore thermally reisomerizes to the 11-cis form upon warming. Photoproducts formerly assigned as lumi- and metaiodopsins [Yoshizawa, T., & Wald, G. (1967) Nature 214, 566-571; Hubbard, R., & Kropf, A. (1959) Nature 183, 448-450] were produced by extensive irradiation of iodopsin at -80 and -40 degrees C, respectively, with red light, but their chromophores were identified to be 7-cis-retinals instead of all-trans-retinals. Thus these photoproducts are artificial byproducts formed as a result of photon absorption by all-trans intermediates. The absorption spectrum of the 7-cis product formed from bovine rhodopsin shows no spectral shift when it is warmed from -80 to 0 degrees C, but the spectrum of 7-cis species formed from iodopsin shifted about 40 nm to the blue at a transition temperature of -60 degrees C. This result indicates a unique chromophore-opsin interaction in iodopsin. Four all-trans intermediates of iodopsin were identified above -80 degrees C under irradiation conditions in which no 7-cis products accumulated. Their absorption maxima were estimated to be approximately 570, approximately 530, approximately 470, and approximately 380 nm. These species should correspond to BL-iodopsin, lumiiodopsin, metaiodopsin I, and metaiodopsin II, respectively, assigned by room temperature laser photolysis [Shichida, Y., Okada, T., Kandori, H., Fukada, Y., & Yoshizawa, T. (1993) Biochemistry 32, 10832-10838].
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
19
pubmed:volume
35
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
14599-607
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed:year
1996
pubmed:articleTitle
Chromophore configuration of iodopsin and its photoproducts formed at low temperatures.
pubmed:affiliation
Department of Biophysics, Faculty of Science, Kyoto University, Japan.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't