l-Phenylalanine ammonia-lyase (PAL) activity is low in the external layers (flavedo) of intact mature grapefruit peel. Flavedo discs evince upon incubation increasing PAL activity and ethylene production. Light has no effect in enhancing PAL activity in discs. Exogenous ethylene stimulates PAL activity in the flavedo of intact mature grapefruits (half maximum stimulation at 15 ppm); such activi...

L-Phenylalanine is one of the essential amino acids that cannot be synthesized in mammals in adequate amounts to meet the requirements for protein synthesis. Fungi and plants are able to synthesize phenylalanine via the shikimic acid pathway. L-Phenylalanine, derived from the shikimic acid pathway, is used directly for protein synthesis in plants or metabolized through the phenylpropanoid pathw...

Freshly harvested tomato fruit (Solanum lycopersicum) were pre-treated with 0, 50, and 100 µM prohexadione-calcium (Pro-Ca) and then stored at 1 °C for 21 days to investigate the effect of Pro-Ca treatment on electrolyte leakage (EL), malondialdehyde (MDA), proline and total phenols contents, and activity of phenylalanine ammonia-lyase (PAL) in relation to chilling injury (CI).Treatment with Pr...

The herbicide glyphosate, N-(phosphonomethyl)glycine, induced phenylalanine ammonia-lyase (PAL) activity in the roots of dark-grown maize seedlings. This enzyme induction was shown to precede glyphosate-reduced fresh weight gain in the roots by 24--48 h. Feeding aromatic amino acids with glyphosate further inhibited growth while slightly lowering glyphosate-enhanced PAL activity. Soluble protei...

Kinetin is used as an elicitor to induce vanillic acid formation in cell suspension cultures of Vanilla planifolia. Maximal induction is observed at a kinetin concentration of 20 micrograms per gram of fresh weight of cells. Vanillic acid synthesis is observed a few hours after elicitation. The effects of kinetin on the activity of some enzymes of the phenylpropanoid pathway, i.e. phenylalanine...

B. Moerschbacher, K. H. Kogel, U. Noll, and H. J. Reisener Institut für Biologie III der RW TH Aachen, W orringer Weg, D-5100 Aachen, Bundesrepublik Deutschland Z. Naturforsch. 41c, 830—838 (1986); received April 4/May 5, 1986 Triticum aestivum, Puccinia graminis f. sp. tritici, Hypersensitive Response, Lignification, Elicitor Several biotic and abiotic elicitors of the hypersensitive reaction ...

The molecular mechanism of enzyme (phenylalanine ammonia-lyase; EC 4.3.1.5) formation mediated by phytochrome in mustard seedlings was investigated by labeling the enzyme with deuterium followed by high resolution CsCl density gradient analysis. A favorable relationship between induced rise of activity and turnover of this short-lived enzyme (half-life 3-4 hr) was achieved by labeling pre-irrad...

The first enzyme of the shikimate pathway, 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase (EC 4.1.2.15), is induced by wounding potato or tomato tissue. The increase in enzyme activity is associated with elevated amounts of the enzyme as determined by immunoblots. The specific wound-induced protein synthesis is preceded by an increase in the mRNA encoding this enzyme. The induced mRNA of ...

Methylaspartate ammonia-lyase (MAL; EC 4.3.1.2) catalyzes the reversible addition of ammonia to mesaconate to yield l-threo-(2S,3S)-3-methylaspartate and l-erythro-(2S,3R)-3-methylaspartate as products. In the proposed minimal mechanism for MAL of Clostridium tetanomorphum, Lys-331 acts as the (S)-specific base catalyst and abstracts the 3S-proton from l-threo-3-methylaspartate, resulting in an...