Articulo
Granulosain I, a cysteine protease isolated from ripe fruits of Solanum granuloso-leprosum (Solanaceae)
Autor
Vallés, Diego
Bruno, Mariela Anahí
López, Laura María Isabel
Caffini, Néstor Oscar
Cantera, Ana María B.
Institución
Resumen
A new cysteine peptidase (Granulosain I) was isolated from ripe fruits of <i>Solanum granuloso-leprosum</i> Dunal (Solanaceae) by means of precipitation with organic solvent and cation exchange chromatography. The enzyme showed a single band by SDS-PAGE, its molecular mass was 24,746 Da (MALDI-TOF/MS) and its isoelectric point was higher than 9.3. It showed maximum activity (more than 90%) in the pH range 7-8.6. Granulosain I was completely inhibited by E-64 and activated by the addition of cysteine or 2-mercaptoethanol, confirming its cysteinic nature. The kinetic studies carried out with PFLNA as substrate, showed an affinity (Km 0.6 mM) slightly lower than those of other known plant cysteine proteases (papain and bromelain). The N-terminal sequence of granulosain I (DRLPASVDWRGKGVLVLVKNQGQC) exhibited a close homology with other cysteine proteases belonging to the C1A family. Facultad de Ciencias Exactas Centro de Investigación de Proteínas Vegetales