Abstract
The work herein describes an investigation into the synthesis, analysis and decomposition of some labelled amino acids and peptides. The work was carried out to investigate the potential of a novel biochemical method for labelling amino acids with hydrogen isotopes and to study the effects of pH on the storage of tritiated amino acid derivatives in aqueous solutions. Chapter One describes the synthesis, analysis and radiation decomposition of tritiated amino acids and peptides. Methods for the preparation of N-acyl-2,3-dldehydroamino acids and N-acyl-2,3-didehydropeptldes via azlactone and azido carboxylic acid intermediates are given. The catalytic reduction of the unsaturated precursors using hydrogen-tritium mixtures has been investigated. The radiation decomposition of N-acetyl-[4,5-35H2]-leucine (3.75Ci/mmol), N-acety1-[2,3-35H2]-phenylalanine (18.2Ci/mmol) and N-benzoyl-[2,3-35H2]-phenylalanlne (12Ci/mmol) in buffer solutions are reported. Analysis of the samples by tritium nmr spectroscopy and radio-tlc analysis revealed that in all cases the majority of radiation decomposition was not at the site of tritium labelling. Chapter Two describes the deuteration of amino acids using Pseudomonas putida cells as a catalyst. Attempts to use semi-purified extracts of methlonine-r-lyase as a catalyst for the deuterium labelling of amino acids were unsuccessful. The immobilization of the bacteria cells using Bioflx C2 support is reported. A wide range of amino acids have been investigated and the results of labelling studies using free and imaobilized cells are compared. Labelling studies using semi-aqueous and non-aqueous solvent media, including the deuteration of glycine esters in dimethylsulphoxlde and dimethylformamide, have been reported.