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Title: Purification and characterization of the pectin lyase secreted within the macerating fluid of Rhizopus oryzae (Went & Prinsen Geerligs) grown on orange peel
Authors: Hamdy, Hossam S
Keywords: cellulase
orange peel
pectin lyase
Rhizopus oryzae
solid state fermentation
Issue Date: Jul-2006
Publisher: CSIR
Series/Report no.: Int Cl.8 C12N19/88; C12R1/845
Abstract: Potentiality of Rhizopus oryzae to utilize orange peel, an inexpensive and low-cost substrate, under solid state fermentation (SSF) conditions to produce macerating fluid with high cellulolytic and pectinolytic activities was confirmed in the present work. Addition of NH4NO3 and NH4Cl to the fermentation medium improved the macerating potentiality due to an increase in cellulase and pectinase levels. The pectin lyase (PL) secreted by R. oryzae was also purified to electrophoretic homogeneity, using ammonium sulfate fractionation and 2-step-column chromatography. The PL was purified 22-folds and its specific activity was 2313 U/mg protein. The purified PL expressed its maximum activity at 50°C and pH 7.5, showed good stability in the pH range of 7 to 9.5 and its midpoint of thermal inactivation (Tm) was recorded at 70°C after 45 min of exposure. Presence of Ca2+ enhanced the activity and thermal stability of the purified PL. Ions of Mg, Na and K showed stimulatory effects on the enzyme activity, while ions of Zn, Co, Mn and Hg were inhibitory. The results suggest that possibly SH group in PL structure participated in the activity of the enzyme. Values of Km, Vmax, Kcat and molecular mass of the purified enzyme were 3.87 mg/mL, 297 U/mL, 5.94 mg U-1 min-1 and 31 kDa, respectively.
Description: 284-291
ISSN: 0975-0967 (Online); 0972-5849 (Print)
Appears in Collections:IJBT Vol.05(3) [July 2006]

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