Bacteriorhodopsin's M sub 412 intermediate contains a 13-cis,14-s-trans,15-anti-retinal Schiff base chromophore

Journal Article · Tue May 02 00:00:00 EDT 1989 · Biochemistry; (USA)

DOI:https://doi.org/10.1021/bi00435a009· OSTI ID:5197280

Ames, J B; Fodor, S P.A.; Gebhard, R; Raap, J; van den Berg, E M.M.; Lugtenburg, J; Mathies, R A ^[1]

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1. Univ. of California, Berkeley (USA)

The structure of the retinal chromophore about the C{double bond}N and C{sub 14}-C{sub 15} bonds in bacteriorhodopsin's M{sub 412} intermediate has been determined by analyzing resonance Raman spectra of {sup 2}H and {sup 13}C isotopic derivatives. Normal mode calculations on 13-cis-retinal Schiff bases demonstrate that the C{sub 15}-D rock and N-C{sub Lys} stretch are strongly coupled for C{double bond}N-syn chromophores and weakly coupled for C{double bond}N-anti chromophores. When the Schiff base geometry is anti, the C{sub 25}-D rock appears as a localized resonance Raman active mode at {approx} 980 cm{sup {minus}1}, which is moderately sensitive to {sup 13}C substitution at positions 14 and 15 ({approx} 7 cm{sup {minus}1}) and insensitive to {sup 13}C substitution at the {epsilon} position of lysine. When the Schiff base geometry is syn, in-phase and out-of-phase combinations of the C{sub 15}-D rock and N-C{sub Lys} stretch are predicted at {approx} 1060 and {approx} 910 cm{sup {minus}1}, respectively. The in-phase mode is more sensitive to {sup 13}C substitution at positions 14 and 15 and at the {epsilon} position of lysine. Calculations and comparison with experimental data on dark-adapted bacteriorhodopsin indicate that the in-phase mode at {approx} 1060 cm{sup {minus}1} carries the majority of the resonance Raman intensity. The authors conclude that M{sub 412} contains a 13-cis,14-s-trans,15-anti chromophore. This result supports the recently proposed C-T model for the mechanism of the proton pump in bacteriorhodopsin.

• OSTI ID: 5197280
• Journal Information: Biochemistry; (USA), Journal Name: Biochemistry; (USA) Vol. 28:9; ISSN 0006-2960; ISSN BICHA
• Country of Publication: United States
• Language: English

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