Evidence for Proteogenic Peptide-like Sequences in Meteorites Through an Enzyme-Catalysed Stereoselective Hydrolysis Strategy

In this manuscript, we evidenced for the first time proteogenic like peptide sequences in meteorite thanks to an original stereoselective enzymatic hydrolysis. Within this framework, we have first characterised the amino acids content of two meteorites, Murchison and Allende, after the standard acid hydrolysis protocol currently used in astronomical studies. To reach this goal, we have developed a highly sensitive chiral LC-MS method and we have highlighted new l- and d-enantiomers, never detected before in both meteorites. These primary findings extend the list of amino acids already found in meteorites. We next investigated the presence of proteogenic like peptide sequences. For that, we have compared the amounts of amino acids l- and d-enantiomers released from either the standard acid hydrolysis or our stereoselective peptidase hydrolysis. Thanks to this strategy, we have highlighted the presence of peptide sequences involving proteogenic l-amino acids in the Murchison together with their absence in Allende, which is consistent with the respective organic content of both meteorites. Furthermore, we demonstrated that the peptide sequences were indigenous to the Murchison meteorite.<br>

Evidence for Proteogenic Peptide-like Sequences in Meteorites Through an Enzyme-Catalysed Stereoselective Hydrolysis Strategy

In this manuscript, we evidenced for the first time proteogenic like peptide sequences in meteorite thanks to an original stereoselective enzymatic hydrolysis. Within this framework, we have first characterised the amino acids content of two meteorites, Murchison and Allende, after the standard acid hydrolysis protocol currently used in astronomical studies. To reach this goal, we have developed a highly sensitive chiral LC-MS method and we have highlighted new l- and d-enantiomers, never detected before in both meteorites. These primary findings extend the list of amino acids already found in meteorites. We next investigated the presence of proteogenic like peptide sequences. For that, we have compared the amounts of amino acids l- and d-enantiomers released from either the standard acid hydrolysis or our stereoselective peptidase hydrolysis. Thanks to this strategy, we have highlighted the presence of peptide sequences involving proteogenic l-amino acids in the Murchison together with their absence in Allende, which is consistent with the respective organic content of both meteorites. Furthermore, we demonstrated that the peptide sequences were indigenous to the Murchison meteorite.<br>

A Comparison of Cellulose Extraction and ABA Pretreatment Methods for AMS 14C Dating of Ancient Wood

We have compared accelerator mass spectrometry (AMS) radiocarbon results on wood samples at or near the limit of 14C dating, pretreated with a standard acid-base-acid (ABA) protocol, with those obtained from cellulose prepared from the same samples by several modifications of the Jayme-Wise cellulose extraction method (Green 1963). These tests were carried out to determine the most efficient way to ensure low backgrounds in 14C measurements of well-preserved ancient wood samples.

pH-Metric Determination of the Acid Value of Vegetable Oils without Titration

The acid value (AV) of vegetable oils is determined without titration by using a new reagent consisting of triethanolamine in a solution of water and isopropyl alcohol. When the oil sample is mixed with the reagent in the pH-metric cell, free fatty acids from the sample are extracted into the reagent ( 3 - 4 min). The initial pH, called conditional pH´, is measured, a standard acid (HC1) is added, and the final pH, pH´2, is measured. AV is calculated from the difference between pH´! and pH´2. The method is applicable for quality control of vegetable oils during their production, trade, and use

University of Granada Radiocarbon Dates VII

This paper includes determinations of archaeological, geological and palaeobotanical samples from Spain and Portugal, measured at the University of Granada Radiocarbon Dating Laboratory, from 1990 to 1991. Pretreatment of charcoal and wood samples is a standard acid-basic procedure using 8% HCl and 2% NaOH at boiling temperature. The collagen of bone samples is obtained by the Longin (1971) method. The method of dating is benzene synthesis and liquid scintillation counting.

University of Granada Radiocarbon Dates VIII

This paper includes determinations of archaeological, geological and paleobotanical samples from Spain and Brazil, measured at the University of Granada Radiocarbon Dating Laboratory, mainly from 1991 to 1992. As previously reported (González-Gómez 1992), pretreatment of charcoal and wood samples is a standard acid-basic procedure using 8% HCl and 2% NaOH at boiling temperature. The collagen of bone samples was extracted by the Longin (1971) method. The method of dating is liquid scintillation counting of synthesized benzene.

University of Granada Radiocarbon Dates VI

This paper includes determinations of archaeological, geological, palaeobotanical and other samples from Spain, Portugal and Bolivia, measured at the University of Granada Radiocarbon Dating Laboratory, mostly from 1989 to 1990. Pretreatment of charcoal and wood samples is a standard acid-basic procedure using 8% HCl and 2% NaOH at boiling temperature. We obtain collagen from bone samples using the Longin (1971) method.

University of Granada Radiocarbon Dates V

This paper includes some determinations of archaeological, art and palaeobotanical samples from Spain and Portugal, obtained at the University of Granada Radiocarbon Dating Laboratory, mostly from 1986 to 1988. Pretreatment of charcoal and wood samples is a standard acid-basic procedure using 8% HC1 and 2% NaOH at boiling temperature. The collagen of bone samples is obtained by the Longin (1971) method.The method of dating is benzene synthesis and liquid scintillation counting as previously reported (González-Gómez, López-González & Domingo-García 1982; González-Gómez, Sánchez-Sánchez and Domingo-García 1985; González-Gómez, Sánchez-Sánchez and Villafranca-Sánchez 1986, 1987).14C activity was measured in a Packard Tri-Carb Mod 4640 liquid scintillation spectrometer, using 20 ml low 40K counting vials with 5 ml benzene and 10 ml PPO-toluene as scintillator with a background of ca. 9 cpm. Efficiency was approximately 70% using the part of spectrum above the end point of tritium.