PURIFICATION AND PROPERTIES OF THE SOLUBLE ACID INVERTASE FROM OR YZA SATIVA

MARIA INES ISLA, GRACIELA SALERNO,*'~ HORACIO PONTIS,*'~ MARTA AMELIA VATTUONE* AND ANTONIO RODOLFO SAMPIETRO

PHYTOCHEMISTRY REVIEWS

SPRINGER

Lugar: Berlin; Año: 1995 vol. 38 p. 321 - 325

1568-7767

An invertase (fl-fructofuranosidase, EC 3.2.1.26) from aerial parts of 17-day-old Oryza sativa plants has beenpurified to homogeneity by gel filtration on Sephadex G-150 and adsorption on brushite. The invertase is a dimericglycoprotein (M, 98 000) composed of two identical subunits (M, 46 000). The pI is ca 6 and the activation energy is8250 cal mol- ~ over 30 ° and 24 000 cal mol- 1 below this temperature. The enzyme shows a high specificity for sucrose(K m 6.6 x 10-3M) and its activity is modulated by fructose. Glucose is a classical non-competitive inhibitor andfructose produces a complex non-linear competitive inhibition. Proteins are activators of the invertase, but they do notsuppress the inhibitory action of the reaction products. The in vitro spontaneous complex formation among invertasesand proteins in higher plants suggests that invertases are functioning complexed with some protein in vivo.