The incorporation of [(14)C]phenylalanine and [1,6-(14)C]shikimic acid into tyrosine was investigated in the callus of Portulaca grandiflora, var. JR (L.). By inhibiting phenylalanine with 1-alpha-aminooxy-beta-phenyl-propionic acid and tyrosinase with 1-cysteine-HCl and hydrazine-hydrate, the possible synthesis of tyrosine from phenylalanine was demonstrated. Tetrahydropterine sulfate was an e...

l-Phenylalanine ammonia-lyase (E.C. 4.3.1.5) from maize is active with l-tyrosine and l-phenylalanine and exhibits atypical Michaelis-Menten kinetics with both substrates. With phenylalanine as a substrate, the pH optimum is 8.7 and with tyrosine, 7.7. The estimated Km at high substrate concentrations is 0.27 mm for phenylalanine and 0.029 mm for tyrosine. However, the V(max) with phenylalanine...

Phenylalanine ammonia-lyase (PAL) links the plant primary and secondary metabolisms, its product, trans-cinnamic acid, is derived into thousands of diverse phenylpropanoids. Bambusa oldhamii BoPAL4 has broad substrate specificity using L-phenylalanine, L-tyrosine, L-3,4-dihydroxy phenylalanine (L-DOPA) as substrates to yield p-coumaric caffeic respectively. The optimum reaction pH for three was...

Abscisic acid (ABA) is one of the plant hormones involved in the interaction between plants and pathogens. In this work, we show that tomato (Lycopersicon esculentum Mill. cv Moneymaker) mutants with reduced ABA levels (sitiens plants) are much more resistant to the necrotrophic fungus Botrytis cinerea than wild-type (WT) plants. Exogenous application of ABA restored susceptibility to B. cinere...

Plant growth and activity of peroxidases (POX) and phenylalanine ammonia-lyase (PAL) were investigated in seedlings of yellow lupine (Lupinus luteus L.) and soybean (Glycine max L.) treated with copper (25 mg/l) and an inhibitor of ethylene biosynthesis (CoCl 2 ). Both lupine and soybean plants stressed with an excess of copper exhibited a decrease in root length and fresh weight. In lupine pla...

The present study was conducted to investigate the allelopathic activity of Rumex dentatus aqueous leaf extract on metabolites, reactive oxygen species (ROS), and enzymes activities in Portulaca oleraceae. results showed a reduction carbohydrates, protein, DNA, RNA contents. However, total phenolics, flavonoids, malondialdehyde were enhanced. ROS such as hydrogen peroxide, superoxide radicals, ...

Wounding lettuce (Lactuca sativa L., var. Longifolia) leaves induced an eight-fold increase in the activity of phenylalanine ammonia-lyase (PAL; EC 4.3.1.5), and the subsequent accumulation of phenolic compounds and tissue browning at 10 C. PAL is a key enzyme in the synthesis of phenolic compounds. A PAL cDNA was previously isolated by reverse-transcription PCR using total RNA from wounded let...