Raman spectra of dilute solutions of some steroisomers of vitamin A type molecules

Rimai, L.; Gill, D.; Parsons, J. L.

doi:10.1021/ja00735a006

Cited by 115 publications

(57 citation statements)

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“…Then, the lines in the spectra of rhodopsin and these photolytic intermediates must be assigned. Previous experimental work (16) and recent rapid flow studies (A. Doukas, R. Callender, T. Yudd, R. Crouch, and K. Nakanishi, to be published) on various isomers of retinal and their Schiff bases are important in this regard, as are theoretical studies (17). Spectra of isotopically substituted retinals and of retinal analogs can also be expected to facilitate the interpretation of the spectra of rhodopsin and its photolytic intermediates (18,19).…”

Section: Prospectsmentioning

confidence: 99%

Rapid-flow resonance Raman spectroscopy of photolabile molecules: rhodopsin and isorhodopsin.

Mathies¹,

Oseroff²,

Stryer³

1976

Proc. Natl. Acad. Sci. U.S.A.

201

145

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We have devised a method for obtaining the resonance Raman spectrum of a photolabile molecule before it is modified by light. The essence of this technique is that the sample is flowed through the light beam at a sufficiently high velocity so that the fraction of photoisomerized (or photodestroyed) molecules in the illuminated volume is very low.This rapid-flow technique has enabled us to measure the resonance Raman spectrum of unphotolyzed bovine rhodopsin in Ammonyx LO detergent solution and in sonicated retinal disc membranes. The major features of these spectra, which are very similar to one another, are the protonated Schiff base line near 1660 cm-1, the ethylenic line at 1545 cm-, lines due to skeletal modes at 1216, 1240, and 1270 cm-l, and a line due to C-H bending at 971 cm-'. The resonance Raman spectrum of unphotolyzed isorhodopsin formed by the addition of 9-cis-retinal to opsin was also measured. The spectrum of isorhodopsin is more complex and differs markedly from that of rhodopsin. In isorhodopsin, the ethylenic line is shifted to 1550 cm-l, and there are six lines between 1153 and 1318 cm-'. The rapid-flow technique described here makes it feasible to control the extent of interaction between light and any photolabile molecule. We present a theory for predicting the effective sample composition in the illuminated volume as a function of the flow rate, light intensity, and spectral characteristics of the photolabile species. Resonance Raman spectroscopy takes advantage of the selective enhancement in Raman scattering from vibrations coupled to an electronic transition when the excitation wavelength is within or near the corresponding absorption band (1, 2). This resonance effect makes it possible to specifically monitor the structure of chromophoric sites in macromolecules. Resonance Raman spectroscopy has recently been used to investigate colored metalloproteins (2-5), bacteriorhodopsin (6, 7), rhodopsin (8, 9), and enzymes with extrinsic chromophores (10, 11).Resonance Raman spectroscopy is a promising technique for elucidating the conformational changes in retinal during the initial stages of visual excitation (8, 9). There is a problem, however, in obtaining the spectrum of a photosensitive molecule such as rhodopsin. Raman scattering is a very weak process (1). Even with resonance enhancement, the probability that a molecule absorbs a photon is orders of magnitude greater than the probability that it scatters a photon by the resonance Raman process. It is convenient to express F in terms of the laser power P (photons sec'), which is equal to I 12. Also, we convert from a7A (cm2 molecule-') to the decadic extinction coefficient e (cm-l M-1), which are related by aA = 3.824 X 10-21 e.

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Section: Prospectsmentioning

confidence: 99%

Rapid-flow resonance Raman spectroscopy of photolabile molecules: rhodopsin and isorhodopsin.

Mathies¹,

Oseroff²,

Stryer³

1976

Proc. Natl. Acad. Sci. U.S.A.

201

145

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“…1) 100-200 times per sec. The net result of this photochemical cycle is to pump protons across the cell membrane, which sets up an electrochemical gradient that is thought to drive the synthesis of ATP (7).Resonance Raman spectroscopy has been used to probe the structure of bacteriorhodopsin (8-11), rhodopsin (12-17), and the chromophore of both species, isomers of retinal (18)(19)(20)21 The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U. S. C. §1734 solely to indicate this fact.…”

mentioning

confidence: 99%

Time-resolved resonance Raman spectroscopy of bacteriorhodopsin on the millisecond timescale.

Terner¹,

Campion²,

El‐Sayed³

1977

Proc. Natl. Acad. Sci. U.S.A.

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A simple technique is described that uses a continuous wave laser with electromechanical modulation to obtain time-resolved Raman spectra of transient species on the millisecond timescale. The time behavior of the vibrational bands of the intermediates involved in the proton pumping of bacteriorhodopsin is determined. From these results, along with resonance enhancement and power dependence studies, the bands that appear in the continuous wave Raman spectrum of bacteriorhodopsin can be assigned to three intermediates in the photochemical cycle of bacteriorhodopsin, bR570, bL550, and bM412. The Raman spectra of bR570 and bM412 are compared with published spectra of model Schiff bases of all-trans and 13-cis retinal.Several papers have described the use of time-resolved Raman spectroscopy to obtain vibrational and kinetic information about transient species. Resonance Raman spectra have been obtained of the short-lived free radical p-terphenyl anion (1) and FeCO3 in pulsed magnetic fields (2). Intermediates of bacteriorhodopsin have been studied on the microsecond (3, 4) and nanosecond (5) timescales. In this paper we describe work on bacteriorhodopsin in the millisecond range.Bacteriorhodopsin is found in purple patches of the cell membrane of various species of halophilic bacteria. Discovered in 1971 by Oesterhelt and Stoeckenius (6), it is the only other photosynthetic system, besides the chlorophylls, known to exist in nature. Bacteriorhodopsin is structurally similar to the visual pigment rhodopsin but its biological role is quite different. Under illumination, bacteriorhodopsin cycles through several intermediates ( Fig. 1) 100-200 times per sec. The net result of this photochemical cycle is to pump protons across the cell membrane, which sets up an electrochemical gradient that is thought to drive the synthesis of ATP (7).Resonance Raman spectroscopy has been used to probe the structure of bacteriorhodopsin (8-11), rhodopsin (12-17), and the chromophore of both species, isomers of retinal (18)(19)(20)21 The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U. S. C. §1734 solely to indicate this fact.

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“…Since the comparison between the CCl, solution spectrum and the protein-bound data was essentially identical to the other two derivatives, these data are not shown and are only taken as supporting the conclusion based on retinal and retinol. Hydrogen bonding patterns described here for retinal could not be observed with retinoic acid, since the carbonyl stretching mode of this molecule is too weak to be detected with Raman spectroscopy (data not shown, see Rimai et al, 1971 ;Chiara and Waddle, 1980).…”

Section: Spectroscopymentioning

confidence: 66%

“…Since retinoids are lightsensitive, these spectra were obtained with an excitation frequency in the far red (676.4nm), which was previously shown to cause no photo-alteration (Callender et al, 1976;Curry et al, 1982;and see below). It has been known for many years (Rimai et al, 1971), that the Raman spectra of vitamin A derivatives are sensitive to the isomeric configuration of the polyene chain and the terminal group. Substantial progress has been made in understanding the vibrational nor- ma1 modes of these molecules, particularly those of retinal isomers (cf.…”

Section: Resultsmentioning

confidence: 99%

“…Conclusive support for this hypothesis awaits elucidation of the three-dimensional structure of the apo-protein. However, it is interesting to note in this regard that in fatty-acid-binding protein, a different protein which binds hydrophobic ligands, water molecules which are observed in the X-ray structure of the apo-protein-binding site are displaced upon ligand binding (Sacchettini et al, 1989).…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

The interactions of retinoids with retinol‐binding protein

Manor

Callender

Noy

1993

European Journal of Biochemistry

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We have measured the pre-resonance Raman spectrum of retinal, retinoic acid and retinol in dilute CCl, solutions and when bound to the bovine-serum retinol-binding protein. The comparison reveals that the binding interaction does not involve any specific interactions of the head group and/ or the polyene chain with a particular protein residue. The data indicate hydrogen bonding of bound retinal's head-group oxygen to water, as well as some torsional angle change of its polyene chain upon binding.Retinol (vitamin A alcohol) circulates in blood bound to retinol-binding protein (RBP), a single polypeptide with a molecular mass of 21 kDa that has a single binding site for retinoids (Goodman, 1984). In the circulation, holo-RBP is complexed with another plasma protein, transthyretin. The three-dimensional structure of holo-RBP was determined by X-ray crystallography, and shows that it is composed of a single globular domain comprised of an N-terminal coil, a asheet core, an a-helix, and a C-terminal coil (Cowan et al., 1990;Newcomer et al., 1984). The core of RBP is composed of eight antiparallel p strands which are arranged in two stacked orthogonal p sheets. Retinol is encapsulated within the j? sheets with the p-ionone ring positioned deep within the /? barrel and the isoprene tail extending along the barrel axis to near the surface of the protein.The selectivity of RBP for binding various retinoids and other hydrophobic compounds has been hard to decipher from competition experiments despite intensive efforts. While some groups reported similar affinity of RBP for retinol, citral and p-ionone (Hase et al., 1976), and interpreted the results to indicate lack of a requirement for a fixed polyene chain length, others (Honvitz and Heller, 1974) reported no binding of p-ionone, deducing the opposite conclusion. The isomeric conformation of retinoids was reported to have no effect on binding in some cases (Horwitz and Heller, 1973) and to completely inhibit binding in others (Siegenthaler and Saurat, 1987). Similarly, conflicting reports were published regarding the necessity of a six-membered ring structure as well as a specific requirement of the polar group on the isoprene tail (Goodman and Raz, 1972;Hase et al., 1976; Honvitz and Heller, 1974 recent study of the thermodynamic parameters that contribute to the binding of retinol to RBP have shown that binding is stabilized purely by an increase in entropy and that the enthalpy of binding is approximately zero (Noy and Xu, 1990). These results were interpreted to indicate that binding is mainly stabilized by hydrophobic interactions, and that the hydroxyl moiety of retinol does not play a role in binding to RBP.An ideal method for study of chromophores embedded in proteins is resonance Raman spectroscopy. In this form of vibrational spectroscopy, the spectrum of a molecule is selectively probed by choosing an excitation light which overlaps the electronic absorption band of a chromophore. The resonantly enhanced Raman cross section is hence much larger than that of...

show abstract

Raman spectra of dilute solutions of some steroisomers of vitamin A type molecules

Cited by 115 publications

References 1 publication

Rapid-flow resonance Raman spectroscopy of photolabile molecules: rhodopsin and isorhodopsin.

Rapid-flow resonance Raman spectroscopy of photolabile molecules: rhodopsin and isorhodopsin.

Time-resolved resonance Raman spectroscopy of bacteriorhodopsin on the millisecond timescale.

The interactions of retinoids with retinol‐binding protein

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