Variability in the carbon isotope composition of individual amino acids in plant proteins from different sources: 1 Leaves

Abstract

The natural carbon isotope composition of individual amino acids from plant leaf proteins has been measured to establish potential sources of variability. The plant leaves studied, taken from a range of plant groups (forbs, trees, grasses, and freshwater aquatic plants), showed no significant influence of either season or environment (water and light availability) on their Δδ(13)C values. Plant groups did, however, differ in carbon isotope composition, although no consistent differences were identified at the species level. A discriminant analysis model was constructed which allowed leaves from (1) nettles, (2) Pooideae, (3) other Poales, (4) trees and (5) freshwater higher plants to be distinguished from each other on the basis of their natural abundance (13)C/(12)C ratios of individual amino acids. Differences in carbon isotope composition are known to be retained, to some extent, in the tissues of their consumers, and hence an understanding of compound-specific variation in (13)C/(12)C fractional abundance in plants has the potential to provide dietary insights of value in archaeological and ecological studies.

Abiotic and Biological Degradation of Atmospheric Proteinaceous Matter Can Contribute Significantly to Dissolved Amino Acids in Wet Deposition

“…The relative predominance of Gly among dissolved proteinaceous matter has been reported by Yan et al for precipitation samples collected from a coastal rural area of Korea (3.4–462.0 nM) and a coastal urban site in Korea (6.4–653.0 nM). It was also well documented that Gly represented major fractions in both aerosol FAA and CAA pools. ,,, Gly is substantially enriched in animal fibrous proteins (collagen), elastin, and certain keratins as well as in plant tissues. ,,, Because Gly lacks an oxidation-sensitive side chain, the low steric hindrance for the initial radical generation on the polypeptide backbone can facilitate its release from the peptide chain, particularly when it is in the carbon-terminal region. , Moreover, Gly has been reported to show low photochemical reactivity, with a half-life over 2000 h in the aqueous phase (in contrast, the value is 23 h for Tyr and 21 h for Phe). , Therefore, Gly is one of the most abundant AAs for dissolved proteinaceous matter in precipitation.…”

Evidence for herbivorous cave bears (Ursus spelaeus) in Goyet Cave, Belgium: implications for palaeodietary reconstruction of fossil bears using amino acid δ15N approaches

“…In the future, d 15 N values of amino acids such as valine may be used in fingerprinting feeding habits of animals, especially herbivores, as has already been suggested in studies of d 13 C values of individual amino acids in plants (e.g. Lynch et al, 2016).…”

Natural Carbon Isotope Composition Distinguishes Compound Groups of Biogenic Volatile Organic Compounds (BVOC) in Two Mediterranean Woody Species

“…This however, is a very broad statement and inconsistent with the measured δ 13 C values for benzaldehyde and durene in our study ( Table 2). In a recent study, Lynch et al (2016) investigated the carbon isotope composition of different amino acids in various plants, revealing that the aromatic amino acids phenylalanine and tyrosin were depleted by 1 to 4‰ in 13 C compared to the average δ 13 C value of all investigated amino acids. Gleixner et al (1998) even reported δ 13 C values of −37.2‰ in leaves and −38.1‰ in tubers of Solanum tuberosum for phenylalanine.…”

“…As plants are usually growing in an open system, where the substrate CO 2 is infinite and the resulting products are constantly eliminated by emission, isotopic fractionation is likely to occur (Schmidt et al, 2015). This approach has been successfully applied in the past, elucidating differences in δ 13 C values of various primary and secondary plant metabolites, such as sucrose, starch, lipids, lignin or amino acids (Gleixner et al, 1993(Gleixner et al, , 1998Schmidt and Kexel, 1998;Lynch et al, 2016). An example is given by the pyruvate dehydrogenase involved in the cytosolic mevalonic acid (MVA) pathway, which has a natural preference for 12 C, producing 13 C-depleted acetyl CoA (Melzer and Schmidt, 1987) as a precursor for the resulting sesquiterpenoids (Jux et al, 2001;Tholl, 2015).…”