0000000000751582
AUTHOR
Francine Javelle
showing 4 related works from this author
Characterization and purification of a bacterial chlorogenic acid esterase detected during the extraction of chlorogenic acid from arbuscular mycorrh…
2016
International audience; A Gram-negative bacterium able to grow using chlorogenic acid (5-caffeoylquinic acid) as sole carbon source has been isolated from the roots of tomato plants inoculated with the arbuscular mycorrhizal fungus Rhizophagus irregularis. An intracellular esterase exhibiting very high affinity (K-m = 2 mu M) for chlorogenic acid has been extracted and purified by FPLC from the chlorogenate-grown cultures of this bacterium. The molecular mass of the purified esterase determined by SDS-PAGE was 61 kDa and its isoelectric point determined by chromatofocusing was 7.75. The esterase hydrolysed chlorogenic acid analogues (caffeoylshikimate, and the 4- and 3-caffeoylquinic acid i…
Detection of an O-methyltransferase synthesising acetosyringone in methyl jasmonate-treated tobacco cell-suspensions cultures.
2013
Acetosyringone (3',5'-dimethoxy-4'-hydroxyacetophenone) is a well-known and very effective inducer of the virulence genes of Agrobacterium tumefaciens but the precise pathway of its biosynthesis in plants is still unknown. We have used two tobacco cell lines, cultured in suspension and exhibiting different patterns of accumulation of acetosyringone in their culture medium upon treatment with methyl jasmonate, to study different steps of acetosyringone biosynthesis. In the two cell lines studied, treatment with 100 mu M methyl jasmonate triggered a rapid and transient increase in acetovanillone synthase activity followed by a progressive increase in S-adenosyl-L-methionine: 5-hydroxyacetovan…
Detection of a plant enzyme exhibiting chlorogenate-dependant caffeoyltransferase activity in methanolic extracts of arbuscular mycorrhizal tomato ro…
2012
When Glomus intraradices-colonised tomato roots were extracted in methanol at 6 degrees C, chlorogenic acid (5-caffeoylquinic acid), naturally present in the extract, was slowly converted by transesterification into methyl caffeate. The progress of the reaction could be monitored by HPLC. The reaction only occurred when the ground roots were left in contact with the hydro-alcoholic extract and required the presence of 15-35% water in the mixture. When the roots were extracted in ethanol, chlorogenic acid was transformed to ethyl caffeate in the same conditions. The reaction was also detected in Glomus mosseae-colonised tomato root extracts. It was also detectable in non-mycorrhizal root ext…
l-Tyrosine β-naphthylamide is a potent competitive inhibitor of tyramine N-(hydroxycinnamoyl)transferase in vitro
2001
L-Tyrosine beta-naphthylamide, a synthetic substrate designed to measure tyrosine aminopeptidase activity, is a potent inhibitor of hydroxycinnamoyl-CoA:tyramine N-(hydroxycinnamoyl)transferase (THT) purified from elicited tobacco cell-suspension cultures. The inhibition is competitive, with the inhibitor binding reversibly to the tyramine binding site of the enzyme. Similar results were obtained with THT extracted from elicited potato cell-suspension cultures. Ki values were found to be 0.66 microM for the enzyme from tobacco and 0.3 microM for the enzyme from potato. L-Tyrosine 7-amido-4-methylcoumarin, a fluorogenic substrate for tyrosine aminopeptidases, the structure of which is close …