PHYSICOCHEMICAL PROPERTIES OF AMARANTH GLOBULINS AND THEIR SENSITIVITY TO PROTEASES

QUIROGA, A.V.; APHALO,P; MARTÍNEZ, E.N; AÑÓN, M.C.

Rosario- Santa Fe

Congreso; XLII Reunión Anual de la Sociedad Argentina de Bioquímica y Biología Molecular.; 2006

Amaranth storage proteins are mainly hexameric globulins of 300 kDa. They are composed of polypeptides of 30 and 20 kDa joined by disulfide bridges. As other storage globulins, they came from a multigene family and exhibit molecular heterogeneity. Amaranth globulins comprised 11S-globulin and globulin-P which showed different physicochemical properties. On the contrary of 11S-globulin, globulin-p presented a great tendency to polymerization. In this work we analyzed the relationship among the physicochemical properties of the two globulins with their sensitivity to proteases and their biological function. Globulin-P and 11S-globulin from germinated and non-germinated seeds were analysed by chromatography, electrophoresis and fluorescence spectroscopy. Their sensitivity to the action of papain, urea and 2-mercaptoethanol was tested. Analyses showed that urea affected in a similar way both globulin structures. On the other hand globulin-p aggregates were more sensitive than 11S-globulin to protease and 2-mercaptoethanol. This results correlated with those from germination analyses which showed that globulin-p suffer higher structural modifications than 11S-globulin during the early mobilization. This might be explained by the presence on the globulin-p surface of unprocessed polypeptides more sensitive to protease action.