Resumen

CAVALITTO, S.F.; HOURS, R.A.  y  MIGNONE, C.F.. A contribution to the characterization of protopectinase SE, an endopolygalacturonase with pectin-releasing activity from Geotrichum klebahnii. Rev. Mex. Ing. Quím [online]. 2014, vol.13, n.1, pp.75-81. ISSN 1665-2738.

Hydrolysis of polygalacturonic acid (1.8 g.L⁻¹ ) with 1.25 mg.L⁻¹ of a commercial preparation (Pectinase SE from Shikibo Ltd., Japan) containing protopectinase SE (PPase-SE) activity for 80 min released a reducing power equivalent to ≈ 400 mg.L⁻¹ of galacturonic acid monohydrate, yielding oligogalacturonates with an average polymerization degree of around 4. Thermostability of PPase-SE was positively affected by enzyme concentration. Enzyme activity of a solution containing 12.5 mg.L⁻¹ of Pectinase SE in 20 mM sodium acetate buffer, pH 5.0, quickly dropped to less than 20 % after 80 s of vortexing. Enzyme pre-incubation (37°C, 30 min) with Ca²⁺, Mg²⁺, Co²⁺, Cu²⁺, Fe²⁺, Zn²⁺ and Mn²⁺ (0.1, 1.0 and 10.0 mM) did not affect the activity except in the case of Cu²⁺ (10 mM). Ca²⁺ (2.5 mM) and Mg²⁺ (2.5 mM) in the reaction mixture caused inhibition and activation, respectively. Ca²⁺ inhibition was partially reverted by Mg²⁺. The enzyme is not inhibited by products. K_m and V_max value for PGA was determined to be 0.198 ± 0.013 g.L⁻¹ and 0.0509 ± 0.0032 µmol.mL⁻¹.min⁻¹ respectively. This K_m value is one of the lowest reported for microbial PGases from different origins.

Palabras llave : endo-polygalacturonase; kinetic characterization; metal inhibition.

        · resumen en Español     · texto en Inglés     · Inglés ( pdf )