Data/hora: 04/06/2024 15:09:33

Provedor de dados: | 61
País: | Brazil
Título: | Isolation of enzymes involved in threonine biosynthesis from sorghum seeds
Autores: | Ferreira,Renato Rodrigues; Vendemiatti,Ariane; Meinhardt,Lyndel Wayne; Lea,Peter John; Azevedo,Ricardo Antunes.
Data: | 2004-08-01
Ano: | 2004
Palavras-chave: | Amino acids; Aspartate kinase; Homoserine dehydrogenase; Lysine; Threonine.
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.
Tipo: | Info:eu-repo/semantics/article
Idioma: | Inglês
Identificador: | http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1677-04202004000200005
Editor: | Brazilian Journal of Plant Physiology
Relação: | 10.1590/S1677-04202004000200005
Formato: | text/html
Fonte: | Brazilian Journal of Plant Physiology  v.16 n.2 2004
Fonte: | info:eu-repo/semantics/openAccess