Structure of the retinal chromophore in 7,9-dicis-rhodopsin

Journal Article · Tue Sep 25 00:00:00 EDT 1990 · Biochemistry; (USA)

DOI:https://doi.org/10.1021/bi00490a015· OSTI ID:5707689

Loppnow, G R; Miley, M E; Mathies, R A ^[1]; Liu, R S.H. ^[2]; Kandori, H; Shichida, Y; Fukada, Y; Yoshizawa, T ^[3]

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1. Univ. of California, Berkeley (USA)
2. Univ. of Hawaii, Honolulu (USA)
3. Kyoto Univ., Sakyo-ku (Japan)

Bovine rhodopsin was bleached and regenerated with 7,9-dicis-retinal to form 7,9-dicis-rhodopsin, which was purified on a concanavalin A affinity column. The absorption maximum of the 7,9-dicis pigment is 453 nm, giving an opsin shift of 1600 cm{sup {minus}1} compared to 2500 cm{sup {minus}1} for 11-cis-rhodopsin and 2400 cm{sup {minus}1} for 9-cis-rhodopsin. Rapid-flow resonance Raman spectra have been obtained of 7,9-dicis-rhodopsin in H{sub 2}O and D{sub 2}O at room temperature. The shift of the 1654-cm{sup {minus}1} C{double bond}N stretch to 1627 cm{sup {minus}1} in D{sub 2}O demonstrates that the Schiff base nitrogen is protonated. The absence of any shift in the 1201-cm{sup {minus}1} mode, which is assigned as the C{sub 14}-C{sub 15} stretch, or of any other C-C stretching modes in D{sub 2}O indicates that the Schiff base C{double bond}N configuration is trans (anti). Assuming that the cyclohexenyl ring binds with the same orientation in 7,9-dicis-, 9-cis-, and 11-cis-rhodopsins, the presence of two cis bonds requires that the N-H bond of the 7,9-dicis chromophore points in the opposite direction from that in the 9-cis or 11-cis pigment. However, the Schiff base C{double bond}NH{sup +} stretching frequency and its D{sub 2}O shift in 7,9-dicis-rhodopsin are very similar to those in 11-cis- and 9-cis-rhodopsin, indicating that the Schiff base electrostatic/hydrogen-bonding environments are effectively the same. The C{double bond}N trans (anti) Schiff base geometry of 7,9-dicis-rhodopsin and the insensitivity of its Schiff base vibrational properties to orientation are rationalized by examining the binding site specificity with molecular modeling.

• OSTI ID: 5707689
• Journal Information: Biochemistry; (USA), Vol. 29:38; ISSN 0006-2960
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
RHODOPSIN
MOLECULAR STRUCTURE
ABSORPTION SPECTROSCOPY
GEOMETRY
HEAVY WATER
PIGMENTS
PURIFICATION
RAMAN SPECTRA
RETINA
SCHIFF BASES
BODY
BODY AREAS
EYES
FACE
HEAD
HYDROGEN COMPOUNDS
IMINES
MATHEMATICS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANS
OXYGEN COMPOUNDS
PROTEINS
SENSE ORGANS
SPECTRA
SPECTROSCOPY
WATER
550201* - Biochemistry- Tracer Techniques