Resumo

DUENAS GOMEZ, YENNY MARITZA; NARVAEZ CUENCA, CARLOS EDUARDO  e  RESTREPO SANCHEZ, LUZ PATRICIA. Searching the Best Conditions for the Extraction and Activity Measurement of Cellulase and Xylanase Extracted from the Yellow Pitaya Fruit Peel (Acanthocereus pitajaya). Acta biol.Colomb. [online]. 2008, vol.13, n.1, pp.217-228. ISSN 0120-548X.

By applying different conservation techniques on yellow pitaya fruit (Acanthocereus pitajaya) it has been found that excessive softening of the peel contributes to the deterioration of the fruit. Due to that both cellulase and xylanase have been related to the softening of the fruit's peel; this work was based on the search of the best conditions not only for the extraction, but also for the activity measurement of both cellulase and xylanase. The best extraction system for both enzymes was 20 mM buffer phosphate, 0.5 M NaCl, pH 7.0. For the cellulase activity measurement it was necessary to incubate during 60 min at 37 ºC, with a volume of raw enzymatic extract of 30 µL, using buffer acetate 100 mM at pH 5,0; the values of apparent K_M and V_MÁX were 0.279 mg/mL and 0.00014 nmol glucose/min, respectively. To determine the xylanase activity it was necessary to incubate during 15 min, at 50 ºC, using 30 µL of raw enzymatic extract at pH 4.0 with 100 mM buffer acetate; the values of apparent K_M and V_MÁX for this enzyme were 0.073 mg/mL and 0.0011 nmol glucose/min, respectively.

Palavras-chave : Cellulase; xylanase; yellow pitaya; Acanthocereus pitajaya; softening.

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