SciELO - Scientific Electronic Library Online

 
vol.12 número3Atividade da sintetase da glutamina e sintase do glutamato em relação a fixação de nitrogênio em Lotus spp.Crescimento e nutrição mineral de Eucalyptus maculata e Eucalyptus urophylla em solução nutritiva com concentração crescente de cobre índice de autoresíndice de assuntospesquisa de artigos
Home Pagelista alfabética de periódicos  

Serviços Personalizados

Journal

Artigo

Indicadores

Links relacionados

Compartilhar


Revista Brasileira de Fisiologia Vegetal

versão impressa ISSN 0103-3131

Resumo

RIBEIRO, MARLUCI; FELIX, CARLOS R.  e  LOZZI, SILENE DE PAULINO. Soybean seed galactinol synthase activity as determined by a novel colorimetric assay. Rev. Bras. Fisiol. Veg. [online]. 2000, vol.12, n.3, pp.203-212. ISSN 0103-3131.  https://doi.org/10.1590/S0103-31312000000300004.

Galactinol synthase (GS) is a key enzyme for the biosynthesis of raffinose oligosaccharides (RO) which are the flatulence factors present in soybean seeds and several other legumes. Understanding of soybean seed GS properties is, therefore, of biotechnological interest. The GS enzyme catalyses formation of galactinol and UDP from UDP-gal and myo-inositol. This enzyme is currently assayed by an isotopic method. We have then idealized a more convenient method for GS assay based on the indirect colorimetric determination of the UDP formed which is then hydrolyzed by exogenous apyrase and the resulting Pi quantified by a modification of the colorimetric method of Fiske & SubbaRow. The color developed is stable, and the method is suitable for detection of very low GS activity. The GS activity profiles of developing soybean seeds determined by the isotopic and the colorimetric methods are closely related. The GS enzyme was partially purified (46-fold) by treatment of seed extract with MnCl2, sequential chromatographies on DEAE-Sepharose, Phenyl-Sepharose CL-4B and Q-Sepharose columns. The crude and the partially purified enzyme showed maximum activity at pH 7.0 and 50 ºC. Dithiothreitol and MnCl2 enhanced considerably the activity of the partially purified enzyme. While UDP-glc could be hydrolyzed by the enzyme at a reative activity corresponding to 49% of that calculated for UDP-gal, UDP-man and sucrose were completely ineffective as alternative substrates.

Palavras-chave : Flatulence; galactinol synthase; colorimetric assay; raffinose oligosaccharides.

        · resumo em Português     · texto em Inglês     · Inglês ( pdf )

 

Creative Commons License Todo o conteúdo deste periódico, exceto onde está identificado, está licenciado sob uma Licença Creative Commons