Syntheses and applications of methionines specifically labelled with stable isotopes

The metabolic fate of the alkyl chain (C-1 to C-4) of methionine (CH3SCH2CH2CH(NH2)COOH) is a topic of current interest. A number of methionines specifically labelled with 2H and 13C have been synthesised, and used in metabolic studies of the metabolism of methionines alkyl chain. After a general introduction to methionine metabolism, with emphasis on the alkyl chain, and to the techniques of isotopic labelling, chapter 2 outlines the materials and methods used in the project. In chapter 3 two syntheses of methyl labelled methionines are presented. Novel syntheses of rac-[3,4-13C2] methionine and rac-[3,4-2H2] stereospecifically labelled methionines are presented in chapter 4. The stereochemistry of the latter materials has been demonstrated by 1H n.m.r. analysis of the dehydromethionines derived from them. Chapter 5 describes an examination of the conversion of 2-(methylthio)-[1-13C] ethanol into 1-chloro-2-(methylthio)ethane by a number of reagents. Chapter 6 describes some chemistry of dehydromethionine, including the complete analysis of its 220 MHz 1H n.m.r. spectrum and the preparation of (S)-methionine-(S)-sulphoxide from (1R,3S)-dehydromethionine. Chapter 7 described an examination, using the labelled methionines of the biosynthesis of ethyl-ene from methionine by microorganisms. The results of a study of the biosynthesis of spermidene from methionine, using rac-[3,4-13C2] methionine are also reported. (author)