Concentration and pH effect on the electronic circular dichroism and anisotropy spectra of aqueous solutions of glyceric acid calcium salt

Abstract

Electronic circular dichroism (ECD) and anisotropy spectra carry information on differential absorption of left-and right-circularly polarized light (LCPL and RCPL) by optically active compounds. This makes them powerful tools for the rapid determination of enantiomeric excesses (ee) in asymmetric synthetic and pharmaceutical chemistry, as well as for predicting the ee inducible by ultraviolet (UV) CPL. The ECD response of a chiral molecule is, however, critically dependent on the properties of the surrounding medium. Here, we report on the first ECD/anisotropy spectra of aqueous solutions of the calcium salt dihydrate of glyceric acid. A systematic study of the effect of the salt concentration and pH on the chiroptical response revealed significant changes and the appearance of a new ECD band of opposite sign. Based on the literature, this can be rationalized by the increase in the relative proportion of free glyceric acid/glycerate to Ca 2+ complexes with glycerate with decreasing salt concentration or pH. Glyceric acid can be readily produced under astrophysical conditions. The anisotropy spectra of the solution containing prevalently the free form of this dihydroxy carboxylic acid resemble the ones of previously investigated aliphatic chain hydroxycarboxylic acids and proteinogenic amino acids. This indicates possible common handedness of stellar CPL-induced asymmetry in the potential comonomers of primitive proto-peptides.alkaline earth metal, chiral hydroxycarboxylic acid, circularly polarized light, complexation, CPL scenario, enantiomeric excess, homochirality | INTRODUCTIONDifferentiation between enantiomers of a chiral species requires a chiral force. Circularly polarized light (CPL) represents a true chiral entity, 1 and the origin of biological homochirality-uniformity of handedness of amino [This article is part of the Special Issue: Chirality in France. See the first articles for this special issue previously published in Volumes 33:9, 33:10, 33:11, 33:12, and 34:1. More special articles will be found in this issue as well as in those to come.]

Chiroptical properties of membrane glycerophospholipids and their chiral backbones

“…Interestingly, replacing the first carbon with a hydroxy group in G3P by a carboxyl (−COOH) or an aldehyde (−CHO) group leads to enhanced anisotropy values at longer wavelengths ( g extrema of ~−0.008 at 228 nm and ~−0.033 at 307 nm, respectively; Figure 4), highlighting possible pathways for indirect chirality transfer to G1P/G3P backbones, which are to be explored. It should be noted that the chiroptical properties of d ‐3‐phosphoglyceric acid in Figure 4 are expected to be affected by complexation with sodium ions present in the standard, as we previously reported for glyceric acid in the presence of calcium ions 36 . Consequently, we expect the maximum anisotropy factor of pure d ‐3‐phosphoglyceric acid to be even higher.…”

“…It should be noted that the chiroptical properties of D-3-phosphoglyceric acid in Figure 4 are expected to be affected by complexation with sodium ions present in the standard, as we previously reported for glyceric acid in the presence of calcium ions. 36 Consequently, we expect the maximum anisotropy factor of pure D-3-phosphoglyceric acid to be even higher. Importantly, for the majority of stars, the UV photon flux is expected to drop in the far UV wavelength range (<177 nm), 12,37 and most of the UV light <200 nm is expected to be absorbed by water molecules in water-dominated interstellar ices, 38 which further emphasizes the advantage of long wavelength range g bands of the carboxylic acid and aldehyde derivatives as opposed to the alcohol.…”

Interstellar formation of glyceric acid [HOCH 2 CH(OH)COOH]—The simplest sugar acid

“…this process involves carbon-carbon bond coupling via recombination of the hydroxycarbonyl radical (hOĊO, 11) with the 1,2-dihydroxyethyl radical (hOĊhch 2 Oh, 17). Glyceric acid (1) serves as a precursor for critical biomolecules including the proteinogenic amino acid serine (4), 2-methyl glyceric acid (7), and lactic acid (15). in contemporary biochemistry, glyceric acid further represents molecular building blocks of 2-phosphoglyceric acid (2) and 3-phosphoglyceric acid (3) via phosphorylation reactions, linking to the tcA cycle (top right) and calvin cycle (bottom right), respectively.…”

“…Since the first identification of the simplest sugar acid-glyceric acid [HOCH 2 CH(OH)COOH, 1]-in the Murchison and Murray meteorites by Cooper et al (1) more than 20 years ago, 1 has been at the center of attention from the astronomy, astrobiology, and laboratory astrochemistry communities (2)(3)(4)(5)(6)(7). 1 plays a key role in contemporary biochemical processes vital to cellular metabolism such as glycolysis (Fig.…”