Chiroptical Properties of Amino Acids: A Density Functional Theory Study

Adrian-Scotto, Martine; Antonczak, Serge; Bredehöft, Jan Hendrik; Hoffmann, Søren Vrønning; Meierhenrich, Uwe J.

doi:10.3390/sym2020934

Cited by 23 publications

(12 citation statements)

References 39 publications

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“…What came as a surprise from the studies of condensed amino acid CD spectra is that the α‐methylated amino acids, isovaline and α‐methyl valine, which showed the highest ee values of left‐handed enantiomers in meteorites, gave CD signals of the opposite sign compared to the family of α‐H amino acids (Figure ). The higher steric hindrance due to the methyl group in the α‐position is assumed to provide dramatic changes in the preferred realized amino acid conformation and its molecular orbitals, probably leading to reversal of the CD band. It was further shown that the molecular environment of amino acids has a great impact on the CD structure; it causes a significant difference in the peak shape and sometimes leads to inversion of the n→π* band by passing from the liquid to an amorphous state …”

Section: Chiroptical Response and Absolute Asymmetric Formation Of Ammentioning

confidence: 99%

Light on Chirality: Absolute Asymmetric Formation of Chiral Molecules Relevant in Prebiotic Evolution

et al. 2016

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Homochirality is a distinct property of living matter manifested by the unichiral molecular units of genetic material and of proteins, namely, d‐deoxyribose and l‐amino acids. These molecular subunits or their precursors have been shown to form under various prebiotic conditions in racemic form. However, the nature of the chiral influence, which results in the first breakage of molecular symmetry, remains unclear. In this respect, the photochemical model of enantioselection has gained particular importance in recent years. In this model, the interaction of circularly polarized light with racemic molecules generated in the interstellar medium is considered to be the main driving force of enantiomeric discrimination in early prebiotic evolution. Cometary ice simulations, l‐enantio‐enriched amino acids in meteorites, and the detection of circularly polarized electromagnetic radiation in star‐forming regions provide evidence for photochirogenesis. The recent discovery of aldehydes in the cometary nucleus of 67P/Churyumov–Gerasimenko by means of the Cometary Sampling and Composition (COSAC) experiment on board the Rosetta lander Philae, along with the detection of aldehydes and aldopentoses (including chiral ribose) in simulated interstellar ice analogues, provide a direct link between laboratory simulations and cometary composition. In the context of these new findings, this review will provide an overview of the role of chiral molecules in prebiotic evolution with special emphasis on their chiroptical properties and absolute asymmetric photosynthesis.

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Section: Chiroptical Response and Absolute Asymmetric Formation Of Ammentioning

confidence: 99%

Light on Chirality: Absolute Asymmetric Formation of Chiral Molecules Relevant in Prebiotic Evolution

et al. 2016

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“…Boltzmann population weighted theoretical CD curves recently confirmed opposite signs for non-ionic l-valine and l-isovaline in the gas phase between 130 and 180 nm. [16] Previous experimental work using a commercial CD photospectrometer indicated the potentially opposite circular dichroic sign of isovaline with valid data down to 180 nm where the absorption became saturated. [17] The aforementioned theoretical spectra of neutral molecules in the gas phase are not directly transferable to interstellar chemistry or our experiments.…”

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

confidence: 99%

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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“…The free energies for each stereoisomer of PC oligomers were obtained by the addition of thermal corrections derived from frequency calculations to the energies of each fully optimized structure in the gas phase and single‐point energies in octanol and water (M05‐2X/6‐31G**, 298 K). [ 32 ] Then, these free energies were used to obtain populations of conformers according to the Boltzmann distribution law represented in the following equation:

\frac{N_{i}}{N} = \frac{e^{- {normalG}_{i} / kT}}{\sum e^{- G_{i} / italickT}} = \frac{e^{- ∆ G / RT}}{\sum e^{- ∆ normalG / italicRT}}

where the natural logarithm of the ratio of the number of molecules in different energy levels at ground state is proportional to the negative of their energy separation. [ 33 ] The variable N i corresponds to a fraction of molecules at a determined conformation at ground state.…”

Section: Methodsmentioning

confidence: 99%

Interactions between procyanidin oligomers and the active form of matrix metalloproteinase‐7: A theoretical insight

Mendoza–Wilson

Balandrán‐Quintana

2020

Int J of Quantum Chemistry

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The objective of this study was to determine the sites and modes of interaction of the most common oligomers of B‐type procyanidins (PCs) with the active form of the matrix metalloproteinase‐7 (MMP‐7) and some molecular properties of the PCs by using theoretical methods. These data may provide useful insights into the ability of PCs to act as selective MMP‐7 inhibitors. Some stereoisomers that predominated in the analyzed PCs (PB2, PC1, tetramer) could act as selective inhibitors of MMP‐7 due to their interaction with amino acids of the subsites S2 and/or S1′ in the active site, and with some specific amino acids of MMP‐7 that bind to cholesterol sulfate to promote proteolysis of the cell membrane. Hydrogen bonding was the main interaction of PB2 and PC1 with MMP‐7, while in the tetramer, the van der Waals interactions prevailed. The determination of molecular properties such as chemical reactivity and stability by the highest occupied molecular orbital and lowest unoccupied molecular orbital gap, revealed that oligomers of PCs acquired very stable poses in their docking with MMP‐7. Polarizability seems to be an important factor for PCs with large molecular volume (PC1, tetramer) to establish contact with amino acids of narrow subsites in the active site (S2, S1′) and amino acids located outside the active site.

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Chiroptical Properties of Amino Acids: A Density Functional Theory Study

Cited by 23 publications

References 39 publications

Light on Chirality: Absolute Asymmetric Formation of Chiral Molecules Relevant in Prebiotic Evolution

Light on Chirality: Absolute Asymmetric Formation of Chiral Molecules Relevant in Prebiotic Evolution

Circular Dichroism of Amino Acids in the Vacuum‐Ultraviolet Region

Interactions between procyanidin oligomers and the active form of matrix metalloproteinase‐7: A theoretical insight

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