G. Goas

Etude de l'activite de l'arginine decarboxylase dans les jeunes plantes de Glycine max privees de leurs cotyledons

Abstract l -Arginine carboxy-lyase and l -ornithine carboxy-lyase activities were investigated in young decotylized Glycine max plants growing in the light on a liquid medium in the presence of ammonium chloride or nitrate. Only the first enzyme could be detected. It had pH optimum at 7.0 activity and there is much more activity in plants cultivated on ammonium chloride than in plants grown on nitrate.

Bound 4-aminobutyric acid in root nodules of Medicago sativa and other nitrogen fixing plants

Abstract Root nodules of a few nitrogen fixing plants, expecially those of Anthyllis vulneraria and Medicago sativa were found to contain between 3.8% and 2.3% of their total dry matter as non-protein nitrogen. Amino-N that represented only a minor fraction of this reduced-N, greatly increased after acid hydrolysis, particularly in the case of M. sativa nodules. This increase in amino-N was related to hydrolysis of bound forms of 4-aminobutyric acid which represented at least 6.6% of the dry matter. Bound forms of 4-aminobutyric acid are considered to be cationic compounds judging by their electrophoretic mobilities in acid conditions and their very strong reaction with the Dragendorffs reagent. Six of them, isolated using conventional amino acid analysis, were studied in respect to their acid stability and their significant content of 4-aminobutyric acid associated with a few other amino acids.

Caractérisation de la sticticine chez le lichen Lobaria laetevirens

Abstract Sticticin has been isolated from the thallus of Lobaria laetevirens . Its structure was determined by spectroscopic methods (NMR, MS) and comparison with a synthetic sample. It has been found in several species of the Stictaceae.

Characterization of dopa betaine, tyrosine betaine and N-dimethyltyrosine from Lobaria laetevirens

Abstract DOPA betaine, tyrosine betaine and N -dimethyltyrosine were isolated from the lichen Lobaria laetevirens . Their structures were determined by ra

Onium Compounds, Amides and Amino Acids Levels in Nodules and Other Organs of Nitrogen Fixing Plants

Summary Considerable levels of typical methylated onium compounds associated with high contents of free proline were detected in root nodules of nitrogen fixing plants adapted to dry habitats. These nodules also contain large quantities of unknown compounds exhibiting some properties related to those of betaines and for wich we propose the name of «onium like compounds». These soluble components could not be found in the root or in other organs of the plants. They might therefore be directly correlated with symbiosis. Among the nitrogenous solutes quantified, asparagine, α-alanine and some uncommon amino acids are the most abundant.