Characterization of an Exopolygalacturonase from Aspergillus niger

Abstract

Polygalacturonase (PGI) from Aspergillus niger NRRL3 was purified about 12.0-fold from the cell-free broth using diethylaminoethyl-Sepharose and Sephacryl S-200 columns. The molecular weight of the PGI was 32,000 Da as estimated by gel filtration and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. PGI had an isoelectric point of 7.6 and an optimum pH of 5.0. PGI was active on polygalacturonic acid and esterified pectins, but the activity on pectin decreased with an increase in degree of esterification. PGI had higher affinity (low Km) and turnover number (Vmax/Km and Kcat/Km) toward polygalacturonic acid. PGI was found to have a temperature optimum at 40 degrees C and was approximately stable up to 30 degrees C. All the examined metal cations had partial inhibitory effects on PGI, while Mn+2 at 5 mM caused a complete inhibition for the enzyme. Comparison of viscosity reduction rates with release of reducing sugars indicated that the enzyme from A. niger is exoacting. The storage stability study of PGI showed that the enzyme in powder form retained 56% of its activity after 9 months of storage at 4 degrees C. The above properties of PGI may be suitable for food processing.

Partial purification and Characterization of Two Pectinases (Polygalacturonase and Pectin lyase) from Papaya Pericarp (Carica papaya cv. solo 8)

“…Maximum polygalacturonase activity at pH 5.0 proves the acidophilic nature of polygalacturonase. The optimum pH of our findings was similar to the pectinase of Penicillium varidictum RFC3 and Aspergillus niger (Silva et al, 2002;Fahmy et al, 2008), respectively. The range of pH at which polygalacturonase activity is maximal is between pH 3.5 and 6.0 (Fenghour et al, 2002;Amande et al, 2013).…”

Purification and Characterization of Alkaline Pectin Lyase from a Newly Isolated Bacillus clausii and Its Application in Elicitation of Plant Disease Resistance

“…Based on their mode of action, pectinases include polygalacturonase, pectin esterase, pectin lyase (PNL), and pectate lyase [4]. Pectinases are classified as an endo-or exo-pectinase depending on whether the cleavages are random or endwise [5]. Pectinases can be broadly classified into acidic and alkaline groups on the basis of pH requirements for optimum enzymatic activity.…”

Production, Purification and Physicochemical Properties of an Exo‑Polygalacturonase from Aspergillus niger SW06

“…21,23 The molecular mass of the PG from A. niger NRRL3 was 32 kDa as estimated by gel filtration and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. 24 In contrast, a heterodimer of 34 and 69 kDa subunit was detected for PG from A. niger MTCC 3323, 9 and two exo-PGs 1 and 2 from another A. niger had the molecular masses of 82 and 56 kDa, respectively. 25 The effect of pH on the A. niger exo-PG activity toward polygalacturonic acid was examined at 45 °C.…”

“…24 The V max of A. niger exo-PG was in the range of V max , i.e., 13.0 to 2600 μmol (mL min) -1 from above three organisms.…”

“…Earlier similar results were obtained that the temperature optima for PGs from other A. niger PGs were around 37 and 45 °C. 9,24,30 The effect of temperature on thermal stability of A. niger exo-PG was investigated by incubation the enzyme for 2 h in 13 mmol L -1 Na 2 HPO 4 -citric acid buffer, pH 5.0 at different temperatures ranging from 30 to 60 °C prior to substrate addition (Figure 5b). In the absence of substrate for 1 h, exo-PG showed 36-89% of the original activity at 30-60 °C.…”