Properties of Phenylalanyl-tRNA Synthetase and Phenylalanine Ammonia-lyase of Pine Suspension Cultures |
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Authors: | JOE R COWLES JO ANN FOWLER |
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Institution: | Department of Biology, University of Houston, Houston, Texas 77004 |
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Abstract: | Phenylalanyl-tRNA synthetase and phenylalanine ammonia-lyase activities were demonstrated in partially purified extracts of pine (Pinus elliottii) suspension cultures. The optimum pH for the phenylalanyl-tRNA synthetase reaction was 7.5 and the optimum ATP and Mg2+ concentrations were 1.0 and 15 mM respectively. Pine, calf liver and yeast tRNA were inadequate substitutes for pea tRNA in the synthetase reaction mixtures. The optimum pH for the phenylalanine ammonia-lyase reaction was 9.0. The Km for phenylalanine was approximately 6.6 × 10?5M. The activity of both enzymes in the partially purified extracts was unstable on storage. |
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