Stable Isotope Geochemistry of Amino Acid Enantiomer Constituents of Fossil System

以前的调查集中在分布和 化石氨基酸成分的立体化学， 印第安人 然而，氨基酸的出现， 所有过去和现在的生物体的组成部分使得它不可能 在这个时候，以准确地确定在多大程度上， 化石中单个氨基酸代表原始物质 生物体产生的能量与外界输入的能量 环境 这次调查的主要目的是 制定一套新的标准， 地球和外星氨基酸的起源 地质材料是基于对稳定的 碳和氮同位素组成的个别D-和 这些材料的氨基酸组分的L-对映体。 到 为了完成这项任务，计划进行一系列实验， 进一步加深了我们对成岩作用的理解 单个氨基酸的稳定同位素组成 对映异构体如下：1）模拟实验，以评估 蛋白质和肽键水解对稳定的 氨基酸的D-和L-对映异构体的同位素组成;和 2)稳定氮碳同位素测定 分离的氨基酸的D-和L-对映体的组合物 化石的各种分子量、蛋白质组分 软体动物 目前，分离和稳定同位素分析 来自化石系统的氨基酸的单个对映体是一种 劳动密集、耗时的过程。 我们将尝试 通过开发一种方法来规避这个问题， 氨基酸对映体稳定同位素分析 通过在线气相色谱/稳定同位素质谱 (GC/西姆斯）。 如果成功，这种方法将彻底改变 科学家利用稳定同位素作为探针的能力 分子水平（例如，阐明动力学同位素效应， 外消旋化过程和生物合成途径 生物系统中氨基酸的形成），并将打开新的 关于进一步了解10 地球外的，生命前的有机合成和2） 地球上生命系统的化学进化

Previous investigations have focused on the distribution and stereochemistry of amino acid constituents of fossils to assess indigeneity. However, the occurrence of amino acids as components of all past and present organisms makes it impossible at this time to precisely determine the extent to which an individual amino acid in a fossil represents original material produced by an organism versus input from the surrounding environment. The primary objective of this investigation is to continue the development of a new set of criteria for evaluating the origin(s) of amino acids in terrestrial and extraterrestrial geologic materials that is based on an assessment of the stable carbon and nitrogen isotope compositions of the individual D- and L-enantiomers of amino acid constituents of these materials. To accomplish this task, a series of experiments are planned to further our understanding of the effects of diagenetic reactions on the stable isotope compositions of individual amino acid enantiomers as follows: 1) simulation experiments to assess the effects of protein and peptide bond hydrolysis on the stable isotope compositions of D- and L-enantiomers of amino acids; and 2) determination of the stable nitrogen and carbon isotope compositions of D- and L-enantiomers of amino acids isolated from various molecular weight, proteinaceous fractions of fossil mollusks. At present, the isolation and stable isotope analysis of individual enantiomers of amino acids from fossil systems is a labor intensive, time consuming process. We will attempt to circumvent this problem by developing a method for the direct stable isotope analysis of quantities of amino acid enantiomers via on-line gas chromatography/stable isotope mass spectrometry (GC/SIMS). If successful, this approach will revolutionize the ability of scientists to utilize stable isotopes as probes at the molecular level (e.g., elucidation kinetic isotope effects, raceminzation processes and biosynthetic pathways for the formation of amino acids in living systems) and will open new doors with respect to furthering our understanding of 10 extraterrestrial, prebiotic organic synthesis and 2) the chemical evolution of living systems on earth.