Henry O. Ajie

Stable hydrogen isotope ratios of saponifiable lipids and cellulose nitrate from cam, c3 and c4 plants

Abstract Hydrogen and carbon isotope ratios of saponifiable lipids and cellulose nitrate from CAM, C 3 , and C 4 plants that grew near one another were determined. The deuterium/protium (D/H) ratios of cellulose nitrate from CAM plants were much higher than those of cellulose nitrate from C 3 and C 4 plants, as has been observed previously. In contrast, the D/H ratios of saponifiable lipids from CAM plants did not differ from those of the same fraction from C 3 and C 4 plants. These observations indicate that deuterium enrichment in cellulose of CAM plants is not caused by any metabolic or physiological process which would lead to deuterium enrichment in all biochemical fractions.

Comparison of bone collagen and osteocalcin for determination of radiocarbon ages and paleodietary reconstruction

Osteocalcin, a gamma-carboxyglutamic acid containing bone protein, is tightly bound to the hydroxyapatite matrix of bone, and as a consequence it is relatively more stable than the dominant protein, collagen. Its distribution in nature is limited to vertebrates. Osteocalcin and collagen have been isolated from modern and fossil bone samples of different organisms in different depositional environments for analysis of their δ13C, δ15N and14C content. Whereas collagen is susceptible t aqueous weathering, hydrolysis, solubilization and removal, as well as contamination by soil amino acids or peptides, osteocalcin is more strongly bonded to the apatite matrix of the bone and hence less prone to loss or replacement by contaminants. We present evidence suggesting that osteocalcin may be a more suitable protein fraction for obtaining accurate14C age estimates and/or δ13C and δ15N for paleodietary reconstruction from bone samples.

AMS radiocarbon dating of bone osteocalcin

Abstract AMS 14C values have been obtained on collagen and osteocalcin fractions in a suite of modern, Holocene and late Pleistocene bone samples of varying collagen content. These studies were undertaken to examine the accuracy of 14C age determinations on osteocalcin in bone samples where collagen and collagen-derived organic products are retained in significantly reduced concentrations. In a series of bones of assumed similar age, large discordances in the 14C values of the osteocalcin and collagen fractions are observed. For the samples we have examined, these discordances are always associated with reduced concentrations of collagen contained in the bones.

Isotopic relationships between saponifiable lipids and cellulose nitrate prepared from red, brown and green algae

Stable carbon and hydrogen isotope ratios were determined for the saponifiable lipid fraction as well as the cellulose fraction (the latter after nitration to remove exchangeable hydrogens) of several species of red, brown and green algae from three locations. A significant correlation was observed between the hydrogen isotope ratios of cellulose nitrate and saponifiable lipid for red algae, but not for brown or green algae. Carbon-13/carbon-12 ratios for both fractions of red algae were in general lower than those observed for brown and green algae. The results reported here are consistent with the proposals that red algae evolved much earlier than and are metabolically different from the brown and green algae.

Radiocarbon Dating of Bone Osteocalcin: Isolating and Characterizing a Non-Collagen Protein

Osteocalcin, a non-collagen bone-matrix protein, has been examined as a possible source of autochthonous 14C data in fossil bones where collagen has been seriously degraded. Extraction procedures for osteocalcin yield a wellcharacterized product that can be clearly distinguished from collagen. The Gla content indicates that osteocalcin is present in the fossil bones at levels similar to the range present in modern bone. However, it appears to be extracted primarily as proteolytic polypeptide fragments rather than as an intact protein. Concordant 14C determinations are obtained on osteocalcin and gelatin extracts from the same bone when the collagen is relatively well preserved. However, increasing discordances in the 14C values of the osteocalcin and gelatin fractions are associated with reduced concentrations of the gelatin extract in the bone.

Modification in amino acids of dead sea scroll parchments

Fragments of Dead Sea Scroll Parchments were extracted for collagen and subjected to amino acid analysis. In modern parchment samples, 90% or more of the protein could be extracted in hot aqueous solution as collagen. In the ancient specimens, 70% or less was extractable. The hot-solution insoluble material was analyzed for collagen. In the soluble extract, the quantity of tyrosine, histidine, and methionine was reduced. Dityrosine was detected. The need to extend such studies is discussed.