Natural Circular Dichroism Spectra of Alanine and Valine Films in Vacuum Ultraviolet Region

Kaneko, Fusae; Yagi-Watanabe, Kazutoshi; Tanaka, Masahito; Nakagawa, Kazumichi

doi:10.1143/jpsj.78.013001

Cited by 30 publications

(58 citation statements)

References 23 publications

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“…The CD spectra of l-alanine, l-valine, and l-leucine are characterized by maxima between 180 and 190 nm (Figure 1 b), l-valine and l-leucine show minima between 160 and 170 nm, and l-serine and l-2-aminobutyric acid show maxima at 165-170 nm (Figure 1 c). The recorded CD spectra are in fair agreement with previous work on alanine and valine enantiomers, [15] where CD spectra were distorted by both linear dichroism attributed to the anisotropic microcrystalline samples and the CD contribution of the enantiomorphic amino acid crystals. We note that the CD spectra of the analyzed a-H l-amino acids are characterized by a maximum between 165 and 185 nm.…”

Section: Dedicated To Professor Henri B Kagan On the Occasion Of Hissupporting

confidence: 89%

“…Such strong bands might be assigned to (p*,p) transitions in the carboxyl group, while (p*,n) transitions were tentatively described to occur above 200 nm. [15] Alternatively, and somewhat unexpectedly, we observed that the electronic CD spectra of the a-methylated amino acids l-isovaline and l-a-methyl valine show negative CD signals over the vacuum-UV spectral range (Figure 1 d). The opposite enantiomers d-isovaline and d-a-methyl valine give positive CD bands of equal magnitude.…”

Section: Dedicated To Professor Henri B Kagan On the Occasion Of Hismentioning

confidence: 67%

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Circular Dichroism of Amino Acids in the Vacuum‐Ultraviolet Region

et al. 2010

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Dedicated to Professor Henri B. Kagan on the occasion of his 80th birthday Biopolymers such as nucleic acids and proteins are composed of chiral monomers that show identical stereochemical configuration. Naturally occurring proteins are made up of l-amino acids.[1] Hypotheses for the origin of symmetry breaking in biomolecules include the absolute asymmetric photochemistry model by which circularly polarized (CP) light induces an enantiomeric excess (ee) in chiral organic molecules. [2][3][4] This model is supported by both the observation of CP light in the star-forming region of Orion [3,5] and the occurrence of l-enantiomer-enriched amino acids in carbonaceous meteorites. [6][7][8] However, the differential absorption of CP light by amino acid enantiomers, which determines the speed and intensity of enantioselective photolysis, is unknown over a large spectral range. Here we show that significant circular dichroic transitions in amino acids can be observed by extending circular dichroism (CD) spectroscopy to the vacuum-ultraviolet (UV) spectral range. a-H amino acids show the same CD magnitude and sign over a large wavelength range. In a given spectral window [9] CP light is therefore capable of inducing enantiomeric excesses of the same handedness into the proteinogenic amino acids we have studied. Absolute asymmetric photochemistry might thus well have triggered the appearance of l-amino acid based life on Earth. Our results demonstrate that enantiomers of "meteoritic" a-methyl amino acids show dichroic absorption with equal magnitude, yet opposite sign to a-H amino acids. Therefore CP light cannot induce l enantiomeric excesses into a-methyl and a-H amino acids as found in meteorites.To explain the cause of symmetry breaking in biomolecules a well-known theory [2-4, 10, 11] proposes that CP interstellar UV radiation-similar to that identified in the starforming region of Orion in the infrared [3,5] -induced enantiomeric excesses into interstellar and circumstellar organic compounds by asymmetric photochemical reactions prior to their deposition on the early Earth. [12] In support of this theory chiral amino acid structures were identified in interstellar ice analogues [13] and a large number of l-enantiomer-enriched amino acids have been identified in the interior of the Murchison [6] and Murray [7] carbonaceous meteorites.[8] To verify the absolute asymmetric photochemistry model the differential CP-light absorption of proteinogenic and meteoritic amino acid enantiomers requires systematic examination.Until now, the popular and extensively used technique of CD spectroscopy has been used to record electronic CD for chiral molecules in aqueous solution above 190 nm.[14] Water absorbs photons of l < 190 nm, making the vacuum-UV region inaccessible for CD spectroscopy in aqueous solution. By using a synchrotron radiation source for CP light and preparing isotropic amorphous solid-state samples immobilized on MgF 2 windows, we have extended electronic CD measurements to the vacuum-UV spectral range.We observed...

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Section: Dedicated To Professor Henri B Kagan On the Occasion Of Hissupporting

confidence: 89%

Section: Dedicated To Professor Henri B Kagan On the Occasion Of Hismentioning

confidence: 67%

Circular Dichroism of Amino Acids in the Vacuum‐Ultraviolet Region

et al. 2010

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“…An earlier attempt has been conducted [32] to obtain an average spectrum that takes into account different possible conformations of an amino acid. In this study, only the two most probable conformations of L-valine, obtained by molecular modelling protocols were considered.…”

Section: Computed Ecd Spectra Of L-valine and L-isovalinementioning

confidence: 99%

“…Several studies, generally at room temperature, were performed in order to measure the vacuum-ultraviolet circular dichroism (VUVCD) spectra of amino and also diamino acids in aqueous solution, using synchrotronradiation CD spectrophotometers [18,19,[30][31][32]. Such instruments are capable of reaching wavelengths under 190 nm, down to 130 nm.…”

Section: Introductionmentioning

confidence: 99%

Chiroptical Properties of Amino Acids: A Density Functional Theory Study

et al. 2010

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Amino acids are involved in many scientific theories elucidating possible origins of life on Earth. One of the challenges when discussing the evolutionary origin of biopolymers such as proteins and oligonucleotides in living organisms is the phenomenon that these polymers implement monomers of exclusively one handedness, a feature called biomolecular homochirality. Many attempts have been made to understand this process of racemic symmetry breaking. Assuming an extraterrestrial origin of the molecular building blocks of living organisms, their susceptibility to asymmetric photolysis by the absorption of circularly polarized electromagnetic radiation in interstellar space was proposed. In order to predict whether the interaction of circularly polarized light with various racemic amino acids can induce an enantiomeric excess, we investigated the electronic and chiroptical properties of the amino acids valine and isovaline by a molecular modelling approach based on quantum chemistry (Density Functional Theory). The average spectra of both L-valine and L-isovaline have been produced on the basis of Boltzmann population analysis using computed spectra for the various conformations of each amino acid.

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“…4,5 We also achieved vuv-CD measurements for amino acid films at wavelength range of 120-220 nm. 9,10 Principle and instrumentation of the measurement have been reported in our previous paper. 4 Recently, we made improvements on our instrumentation in order to achieve more precise measurements.…”

Section: Introductionmentioning

confidence: 99%

Recent progress in vacuum-ultraviolet polarization modulation spectroscopy using polarizing undulator at the TERAS BL5 beamline

Yagi-Watanabe

Tanaka

Kaneko

et al. 2007

Review of Scientific Instruments

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Polarization modulation spectroscopy using an Onuki-type undulator is a useful technique for circular dichroism study in the vacuum-ultraviolet region. We have been developing the vacuum-ultraviolet circular dichroism (vuv-CD) spectroscopy in TERAS BL5 beamline at AIST. This paper describes recent improvements in our instrumentation and methods of analysis to achieve precise and absolute measurements. The CD signal is usually accompanied by experimental artifacts, and elimination of all possible artifacts is the key issue for making reliable measurements. After improving beamline optical system, light flux monitor, and undulator operation method, the base line shift of the CD spectrum is suppressed less than 3x10(-4). Sample manipulation and data processing procedures are also described and absolute CD spectrum can be obtained even for linear anisotropic sample. These progresses lead to more quantitative comparison of experimental with calculation on vuv-CD spectrum.

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Natural Circular Dichroism Spectra of Alanine and Valine Films in Vacuum Ultraviolet Region

Cited by 30 publications

References 23 publications

Circular Dichroism of Amino Acids in the Vacuum‐Ultraviolet Region

Circular Dichroism of Amino Acids in the Vacuum‐Ultraviolet Region

Chiroptical Properties of Amino Acids: A Density Functional Theory Study

Recent progress in vacuum-ultraviolet polarization modulation spectroscopy using polarizing undulator at the TERAS BL5 beamline

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