Etude sur la biosynthèse de Naphtoquinones végétales et bactériennes

Abstract : Quinones are well dispached in nature, in the animal, vegetal and microbial kindom. Those compounds are synthesized from a small number of simple intermediates. The naphtho-quinone ring can be synthesized from four precusrsors: acetate, toluquinone, p-hydroxy-benzoate and shikimate. The aim of this work is the study of vegetal or bacterial naphthoquinone biosynthesis from shikimic acid (trihydroxy-3,4,5 cyclohexen-1 carboxylic acid), and the search for intermediates in this biosynthetic pathway. At the start of our study no experimental data were available and its development was connected to parallel studie from other teams. Some preliminary results had proposed that shikimic acid was a common precursor of aromatic amino-acid, dihydroxy-3,4-benzoic acide, p-amino-benzoic acid, p-hydroxybenzoic acid and menaquinone from Eschericia coli. Thus at the start of this work we know that shikimic acid is totally incorporated in bacterial menaquinones so that the carboxyle becomes a carbonyle of the quinone. Thus three questions need to be answered: - How does the quinonic ring form: where is the carboxylic carbon? - From which precursor commes the three missing carbons? - Is shikimic acid incorporated in the naphtha-quinone symmetrically or selectively? The first question was solved both by Leistner and Zenk and by Leduc et al. in our laboratory using [1,6-14C] shikimic acid. This method implicates laborious and complex degradation of the formed quinines. We have synthesized [3H-3] shikimic acid specifically labeled in a position allowing a simple and univocal degradation. A partial answer to the second question was obtained by Campbell who showed incorporation of three atoms (2,3 and 4) of glutamate into the quinone ring. From his results and the belief that chorismic acid was a precursor we postulated OSB (ortho-succinoyl-benzoic acid), and could synthesize it and prove its incorporation in the naphtoquinones studied (menaquinone, lawsone and juglone). The work in presented in six chapters: the first describes the synthesis of radioactive precursors. The second describes the methods of incorporation of radioactive precursor into quinones, their isolation and their degradation. The three following chapter report the results of incorporation into menaquinone, vegetal naphthoquinones and vegetal anthraquinones. The six chapter discuss the results and proposes a general scheme for shikimic acid derived quinone biosynthesis. At the end an experimental part and some technical add-on are presented.
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Biologie végétale. Université Paris Sud - Paris XI, 1972. Français
Contributor : Patrick Dansette <>
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  • HAL Id : tel-00663831, version 1



Patrick M Dansette. Etude sur la biosynthèse de Naphtoquinones végétales et bactériennes. Biologie végétale. Université Paris Sud - Paris XI, 1972. Français. <tel-00663831>




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