A cycloheximide-sensitive increase in the activity of phenylalanine ammonia-lyase (EC 4.3.1.5) occurs in Xanthium leaf disks exposed to light. Radioactive ammonia-lyase has been isolated by means of sucrose density gradient centrifugation and starch gel electrophoresis from disks fed l-isoleucine-U-(14)C or l-arginine-U-(14)C. The incorporation of radioactive amino acids into phenylalanine ammo...

Both phenylalanine ammonia lyase and tyrosine ammonia lyase were detected in tobacco (Nicotiana tabacum L. Wisconsin 38) callus. The enzymes were separated from each other by Sephadex G-200 column chromatography. Increased activity of tyrosine ammonia lyase was observed during culture of tobacco callus under shoot-forming conditions, while activity of phenylalanine ammonia lyase increased durin...

Inbred weanling rats were maintained on diets containing low (6%), medium (lS%), and high (40%) levels of proteins. After 45 days they were killed and the activities of histidine ammonia lyase, urocanase, and histidine pyruvate aminotransferase in liver were assayed. Histidine ammonia lyase increased with age of the rat, and the increase was proportional to the level of protein in the diet. Ani...

Inbred weanling rats were maintained on diets containing low (6%), medium (lS%), and high (40%) levels of proteins. After 45 days they were killed and the activities of histidine ammonia lyase, urocanase, and histidine pyruvate aminotransferase in liver were assayed. Histidine ammonia lyase increased with age of the rat, and the increase was proportional to the level of protein in the diet. Ani...

The effect of ethylene on the development of phenylalanine ammonia-lyase activity in segments excised from the epicotyl apex of pea seedling was studied. Although there was some increase in phenylalanine ammonia-lyase activity in segments not treated with ethylene, a marked increase in phenylalanine ammonia-lyase activity occurred in ethylene-treated tissues during the incubation. The induction...

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...

Divalent Mn ions cause an increase in the level of phenylalanine ammonia-lyase in gherkin hypocotyls. With the exception of Mg ions, which had a small effect, no other metal ion has so far been found which could replace the Mn ion in this respect. Invertase and peroxidase were not significantly affected by the Mn treatment. The increase in phenylalanine ammonialyase activity is explained by the...

S-peptide (residues 1--14) analogues in which the active histidine-12 residue is replaced by Npi-methyl-L-histidine, Ntau-methyl-L-histidine and beta-(pyrid-3-yl)-L-alanine were synthesized and tested for their capacity to bind to S-protein and to activate it. The results show that both imidazolyl nitrogen atoms are required for optimal catalytic functioning, Ntau being essential to the catalyt...

Because of its key role in secondary phenylpropanoid metabolism, Phe ammonia-lyase is one of the most extensively studied plant enzymes. To provide a basis for detailed structure-function studies, the enzyme from parsley (Petroselinum crispum) was crystallized, and the structure was elucidated at 1.7-A resolution. It contains the unusual electrophilic 4-methylidene-imidazole-5-one group, which ...