RESUMO
Glutaminol adenylate 5 is a competitive inhibitor of glutaminyl-tRNA synthetase with respect to glutamine (Ki = 280 nM) and to ATP (Ki = 860 nM). The corresponding methyl phosphate ester 4 is a weaker inhibitor (Ki approximately 10 microM) with respect to glutamine.
Assuntos
Adenina/análogos & derivados , Adenina/síntese química , Aminoacil-tRNA Sintetases/antagonistas & inibidores , Inibidores Enzimáticos/síntese química , Adenina/química , Adenina/farmacologia , Aminoacil-tRNA Sintetases/metabolismo , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Escherichia coli/efeitos dos fármacos , Escherichia coli/enzimologia , Cinética , Estrutura MolecularRESUMO
Syringolide 2, an elicitor of the bacterial plant pathogen Pseudomonas syringae pv. tomato which triggers a hypersensitive defense response in resistant soybean plants, has been synthesized in five steps via a fructose 1,6-diphosphate aldolase reaction.
Assuntos
Antibacterianos/metabolismo , Frutose-Bifosfato Aldolase/metabolismo , Compostos Heterocíclicos com 3 Anéis/síntese química , Compostos Heterocíclicos com 3 Anéis/metabolismo , Pseudomonas/química , Sesquiterpenos/síntese química , Sesquiterpenos/metabolismo , Alquilação , Animais , Antibacterianos/síntese química , Antibacterianos/química , Compostos Heterocíclicos com 3 Anéis/química , Espectroscopia de Ressonância Magnética , Espectrometria de Massas , Músculo Esquelético/enzimologia , Doenças das Plantas/microbiologia , Coelhos , Sesquiterpenos/química , EstereoisomerismoRESUMO
The stereoselective acylation of meso polyol 2 by vinyl acetate (solvent and acyl donor) in the presence of porcine pancreas lipase gave the corresponding monoester 5 in good yield (76%) and high enantiomeric purity (ee > 98%). The enzymatic reaction was also highly regioselective for a primary alcohol end group, and the two unprotected secondary alcohols were not involved. Compound 5 corresponds to the C(19)-C(27) fragment of rifamycin S.
Assuntos
Álcoois/metabolismo , Fármacos Gastrointestinais/metabolismo , Pancrelipase/metabolismo , Rifamicinas/química , Acilação , Álcoois/química , Antibacterianos/química , Sítios de Ligação , Burkholderia cepacia/enzimologia , RNA Polimerases Dirigidas por DNA/antagonistas & inibidores , Flúor , Espectroscopia de Ressonância Magnética , Modelos Moleculares , Pseudomonas fluorescens/enzimologia , Estereoisomerismo , Compostos de Vinila/metabolismoRESUMO
Carbon dioxide has been previously identified as a critical volatile factor that stimulates hyphal growth ofGigaspora margarita, a vesiculararbuscular mycorrhizal fungus, and we determined the optimal concentration at 2.0%. The beneficial effect of CO2 on fungal development is also visible in the presence of stimulatory (quercetin, myricetin) or inhibitory (naringenin) flavonoids. Sterile root exudates from carrot seedlings stimulate the hyphal development ofG. margarita in the presence of optimal CO2 enrichment. Three flavonols (quercetin, kaempferol, rutin or quercetin 3-rutinoside) and two flavones (apigenin, luteolin) were identified in carrot root exudates by means of HPLC retention time. Flavonols like quercetin and kaempferol are known to have stimulatory effects on hyphal growth ofG. margarita.
RESUMO
Plant phenolic compounds are known to be inducers of virulence genes in plant-pathogen interactions such as those involving Agrobacterium, and flavonoids are known to be inducers or inhibitors of Nod genes in Rhizobium-legume symbiosis. More recent studies suggest that some of these compounds act as molecular signals in the development of vesicular-arbuscular mycorrhizas (VAM). The present study has shown that hyphal growth of the VAM fungus, Gigaspora margarita Becker & Hall, is affected by both stimulatory and inhibitory flavonoids, when applied at 10 µ together with an optimal carbon dioxide enrichment. Stimulatory compounds were all flavonols (kaempferol, quercetin and morin) and possessed at least one hydroxyl group on the B ring. Conversely, two isoflavones (biochanin A, and genistein), a single flavanone (hesperetin) and two compounds without any hydroxyl group on the B ring, galangin (flavonol) and chrysin (flavone), were all inhibitors of hyphal growth.