| Registro completo |
| Provedor de dados: |
Braz. J. Plant Physiol.
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| País: |
Brazil
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| Título: |
Isolation of enzymes involved in threonine biosynthesis from sorghum seeds
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| Autores: |
Ferreira,Renato Rodrigues
Vendemiatti,Ariane
Meinhardt,Lyndel Wayne
Lea,Peter John
Azevedo,Ricardo Antunes
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| Data: |
2004-08-01
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| Ano: |
2004
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| Palavras-chave: |
Amino acids
Aspartate kinase
Homoserine dehydrogenase
Lysine
Threonine
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| Resumo: |
Cereal seeds are poor in essential amino acids, particularly lysine, tryptophan and threonine. The amino acids lysine and threonine are synthesized in the aspartate pathway. Although most of the enzymes of the aspartate pathway have been isolated and characterized in higher plant species, the metabolism of lysine and threonine is totally unknown in sorghum. We have isolated two enzymes, aspartate kinase (AK) and homoserine dehydrogenase (HSDH) from sorghum. Optimum assay conditions were established for the determination of AK and HSDH activities. The highest level of activity was observed in immature seeds. AK was shown to be inhibited by threonine and lysine indicating the existence of at least two isoenzymes, one sensitive to threonine inhibition and the other sensitive to lysine inhibition with the latter being predominant in sorghum seeds. HSDH was shown to be inhibited by threonine indicating the existence of a threonine-sensitive HSDH, however, most of the activity was not inhibited by threonine, suggesting the existence of a second predominant isoenzyme of HSDH resistant to threonine inhibition.
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| Tipo: |
Info:eu-repo/semantics/article
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| Idioma: |
Inglês
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| Identificador: |
http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1677-04202004000200005
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| Editor: |
Brazilian Journal of Plant Physiology
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| Relação: |
10.1590/S1677-04202004000200005
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| Formato: |
text/html
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| Fonte: |
Brazilian Journal of Plant Physiology v.16 n.2 2004
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| Direitos: |
info:eu-repo/semantics/openAccess
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