Abstract

RODRIGUEZ NIETO, JEIMMY MARCELA  and  RESTREPO SANCHEZ, LUZ PATRICIA. Exytraction of Pectic Enzymes from of Lulo(Solanum quitoense Lam) Involved in Softening. Acta biol.Colomb. [online]. 2011, vol.16, n.2, pp.193-204. ISSN 0120-548X.

The main problem of post-harvest deterioration of lulo (Solanum quitoense Lam) is the softening is the main problem of post-harvest deteriorarion of Lulo, that is generated mainly by the activity of pectic enzymes, which attack the structural network of the cell wall. This research was based on finding the best conditions structural cell wall network for extraction and measurement of enzyme activity pectinesterase (PE), polygalacturonase (PG) and pectato liasa (PL); tools needed to study the further role of these enzymes in the deterioration of pectatelyase fruit softening, due to various metabolic changes. It was found that the first two enzymes can be extracted simultaneously with 20 mM phosphate buffer pH 7.0, 0.06 M NaCl and 60 minutes of extraction, ratio 1:2 (plant material: extraction buffer), pectatelyase extracted with 20 mM phosphate buffer pH 7.0, 20 mM cysteine and 30 minutes of extraction, ratio 1:3. For quantification of pectinesterase activity is necessary to incubate 15 minutes at 42 ° C, 2500 µL of crude enzyme extract (EE) in 20 mM phosphate buffer pH 7.0, to 0.15 M NaCl and 1.6% citrus pectin as (CP) substrate with apparent Km values of 3.78% CP and Vmax 17.95 mol H⁺/min * mg prot. For the quantification of pectinesterase activity is necessary to incubate 15 minutes to 42 °C 2500 µL of crude enzyme extract (EE) in 20 mM phosphate buffer pH 7.0, 0.15 M NaCl and 1.6% citrus pectin as substrate with apparent Km values of 3.78% CP and 17.95 µ Vmax mol H⁺/min*mg prot. For the quantification of polygalacturonase activity is necessary to incubate 15 minutes to 37 °C 30 µL (EE) in 200 mM Acetate buffer pH 4.5, 0.25 M NaCl and 1.0% of APG as substrate, with apparent Km values 0.141% of APG and Vmax 28.46 nKat/s*mg prot. For the quantification of the pectatelyase activity is necessary to incubate 2 minutes to 17 °C, 100 µL (EE) in buffer TRIS: HCl pH 8.5, 50 mM 4 mM CaCl2 and 0.1% PGA as substrate, with apparent Km values 0.0865% of APG and Vmax 82.75 µg/s*mg prot.

Keywords : Lulo (Solanum quitoense Lam); softening; pectinesterase; polygalacturonase; pectatelyase.

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