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On the Bioactive Conformation of the Rhodopsin Chromophore: Absolute Sense of Twist around the 6‐ s‐cis Bond
Author(s) -
Fujimoto Yukari,
Ishihara Jun,
Maki Shojiro,
Fujioka Naoko,
Wang Tao,
Furuta Takumi,
Fishkin Nathan,
Borhan Babak,
Berova Nina,
Nakanishi Koji
Publication year - 2001
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/1521-3765(20011001)7:19<4198::aid-chem4198>3.0.co;2-x
Subject(s) - rhodopsin , photoisomerization , chromophore , chemistry , moiety , pigment , stereochemistry , double bond , opsin , polyene , ring (chemistry) , retinal , photochemistry , isomerization , biochemistry , organic chemistry , polymer chemistry , catalysis
Incubation of opsin with synthetic 6‐s‐locked retinoids 2 a and 2 b only led to pigment formation from the alpha‐locked 2 a , the CD spectrum of which was similar to that of native rhodopsin (Rh). This establishes that the 6‐ s ‐bond of the chromophore in rhodopsin is cis , and that its helicity is negative. Earlier cross‐linking studies showed that the 11‐ cis to all‐ trans photoisomerization occurring in the batho‐Rh to lumi‐Rh conversion induces a flip over of the side carrying the ring moiety. The GTP‐binding assay of pigment Rh‐( 2 a ), incorporating retinal analogue 2 a , has shown that its activity is 80 % that of the native pigment. That is, the overall conformation around the 6‐ s bond is retained in the steps leading to G‐protein activation.