RESUMEN
A simple method for the visualisation of wine yeast esterase (carboxylesterase EC 3.1.1.1) activity on electrophoretic gels was developed, using the fluorescent substrate fluorescein diacetate. The zymogram system allows a sensitive detection of esterase bands in only 5 min of incubation of both native and sodium dodecyl sulfate gels.
Asunto(s)
Hidrolasas de Éster Carboxílico/metabolismo , Saccharomyces cerevisiae/enzimología , Carboxilesterasa , Electroforesis en Gel de Poliacrilamida/métodos , Fluoresceínas , Dodecil Sulfato de Sodio , Especificidad por SustratoRESUMEN
Soybean milk, which serves as a base for a variety of beverages, contains raffinose, stachyose, pentanal and n-hexanal; the former two may be responsible for flatulence after fermentation, whilst the latter two for a beany flavour. Twenty-seven strains of Bifidobacterium were analyzed for their alpha-galactosidase activity and the production of lactic and acetic acids to determine their potential for use in the production of fermented soymilk. The behaviour of three strains in soymilk was studied to determine their ability to reduce alpha-D-galactosyl oligosaccharides and produce lactic and acetic acids. They all were able to reduce stachyose and raffinose. Pentanal and n-hexanal were metabolized by Bifidobacterium breve MB233. These data indicate that bifidobacteria can be used for biotechnological processes that employ soymilk as the substrate. A product with low levels of alpha-D-galactosyl oligosaccharides and alkylic aldehydes may be obtained.
Asunto(s)
Bifidobacterium/clasificación , Glycine max/metabolismo , Leche/metabolismo , alfa-Galactosidasa/metabolismo , Ácido Acético/metabolismo , Aldehídos/metabolismo , Animales , Bifidobacterium/enzimología , Cromatografía Líquida de Alta Presión , Fermentación , Ácido Láctico/biosíntesis , Oligosacáridos/metabolismo , Rafinosa/metabolismoRESUMEN
Malolactic activity from Leuconostoc oenos ML34 is tightly associated with lactic dehydrogenase. A simple and fast procedure, involving affinity chromatography on agarose-hexane-NAD (Agnad), was used to separate malolactic activity from lactic dehydrogenase and other proteins. The yield was ca. 86%, the purification was 5.2-fold, and the K(m) values for l-malate, NAD and Mn were 2.8, 0.13, and 0.028 mM, respectively, at a pH optimum of 5.8.