Publications

• Kinetic and regulatory properties of arogenate dehydratase in seedlings of Sorghum bicolor (L.) Moench.

  Siehl D.L., Conn E.E.

  Arogenate dehydratase was purified sixfold from an extract of etiolated seedlings of Sorghum bicolor. Prephenate dehydratase was not detected. The arogenate dehydratase activity displayed hyperbolic substrate kinetics with a KM for arogenate of 0.32 mM. Activity was inhibited competitively by phen ... >> More

  Arogenate dehydratase was purified sixfold from an extract of etiolated seedlings of Sorghum bicolor. Prephenate dehydratase was not detected. The arogenate dehydratase activity displayed hyperbolic substrate kinetics with a KM for arogenate of 0.32 mM. Activity was inhibited competitively by phenylalanine and was stimulated by tyrosine. The low KI for phenylalanine (24 microM) and KA for tyrosine (2.5 microM) indicated a high affinity of the enzyme for these effectors. These results establish the routing of metabolites in phenylalanine biosynthesis in sorghum as proceeding via arogenate rather than phenylpyruvate. << Less

  Arch Biochem Biophys 260:822-829(1988) [PubMed] [EuropePMC]

• Phenylalanine biosynthesis in Arabidopsis thaliana. Identification and characterization of arogenate dehydratases.

  Cho M.-H., Corea O.R.A., Yang H., Bedgar D.L., Laskar D.D., Anterola A.M., Moog-Anterola F.A., Hood R.L., Kohalmi S.E., Bernards M.A., Kang C., Davin L.B., Lewis N.G.

  There is much uncertainty as to whether plants use arogenate, phenylpyruvate, or both as obligatory intermediates in Phe biosynthesis, an essential dietary amino acid for humans. This is because both prephenate and arogenate have been reported to undergo decarboxylative dehydration in plants via t ... >> More

  There is much uncertainty as to whether plants use arogenate, phenylpyruvate, or both as obligatory intermediates in Phe biosynthesis, an essential dietary amino acid for humans. This is because both prephenate and arogenate have been reported to undergo decarboxylative dehydration in plants via the action of either arogenate (ADT) or prephenate (PDT) dehydratases; however, neither enzyme(s) nor encoding gene(s) have been isolated and/or functionally characterized. An in silico data mining approach was thus undertaken to attempt to identify the dehydratase(s) involved in Phe formation in Arabidopsis, based on sequence similarity of PDT-like and ACT-like domains in bacteria. This data mining approach suggested that there are six PDT-like homologues in Arabidopsis, whose phylogenetic analyses separated them into three distinct subgroups. All six genes were cloned and subsequently established to be expressed in all tissues examined. Each was then expressed as a Nus fusion recombinant protein in Escherichia coli, with their substrate specificities measured in vitro. Three of the resulting recombinant proteins, encoded by ADT1 (At1g11790), ADT2 (At3g07630), and ADT6 (At1g08250), more efficiently utilized arogenate than prephenate, whereas the remaining three, ADT3 (At2g27820), ADT4 (At3g44720), and ADT5 (At5g22630) essentially only employed arogenate. ADT1, ADT2, and ADT6 had k(cat)/Km values of 1050, 7650, and 1560 M(-1) S(-1) for arogenate versus 38, 240, and 16 M(-1) S(-1) for prephenate, respectively. By contrast, the remaining three, ADT3, ADT4, and ADT5, had k(cat)/Km values of 1140, 490, and 620 M(-1) S(-1), with prephenate not serving as a substrate unless excess recombinant protein (>150 microg/assay) was used. All six genes, and their corresponding proteins, are thus provisionally classified as arogenate dehydratases and designated ADT1-ADT6. << Less

  J. Biol. Chem. 282:30827-30835(2007) [PubMed] [EuropePMC]

• Arogenate dehydratase.

  Fischer R., Jensen R.

  Methods Enzymol 142:495-502(1987) [PubMed] [EuropePMC]