The pectic enzymes of Aspergillus niger. 2. Endopolygalacturonase

Abstract

obtained with an inoculum size which does not give maximum mycelial dry weight. The pectic enzymes show a marked increase during the third day of growth, and this point is marked also by the virtually complete utilization of the sucrose originally present in the culture and by a discontinuity in the curve of mycelial dry weight. SUMMARY 1. A method is described for the preparation of a mixture of pectic enzymes with cultures of A8pergillu8 niger. 2. The cultures were produced in stirred fermenters with a medium consisting of 005 % of Na%S04, 02 % of NH4NO,, 2 % of sucrose and 2 % of pectin in a boiled extract of groundnut flour. Fermentation was continued for 5-6 days at 30°. The pH of the culture remained between 3 and 4. 3. The preparations induced virtually complete hydrolysis of pectin. 4. Enzymic preparations obtained from the culture fluid by precipitation with ethanol were more active, on a weight for weight basis, than commercially available materials. We wish to acknowledge the award of research fellowships by the Istituto Superiore di Sanit&. We are grateful to the Direction and staff of the pilot plant of the Institute for the provision of facilities and technical assistance. We would especially like to recognize the encouraging guidance and help of Professor E. B. Chain, F.R.S.

Detection and differentiation of pectic enzyme activity in vitro and in vivo by capillary electrophoresis of products from fluorescent‐labeled substrate

“…Since both labeled dimer and trimer are produced from the hexamer, and the sixth residue is drastically modified by the labeling, it is likely that only a total of four residues is needed for productive binding to the active site. These results are in good agreement with the observation of Koller and Neukom [15] that the pentamer and hexamer of GalA are digested by this enzyme to tri-, di-, and mono-GalA, whereas the tetramer (also investigated by Mill and Tuttobello [16]) gives rise to only trimer and monomer.…”

Studies of pectic enzymes produced byTalaromyces flavus in submerged and solid substrate cultures

“…One activity unit was defined as the amount of enzyme, which releases 1 mmol of reducing sugar per minute, using D-galacturonic acid as standard. Viscositydiminishing activity was determined by measuring the decrease in relative viscosity of a 0.2% (w/v) solution of pectin in buffer A at 50 °C, using an OSTWALD-type viscometer with a water flow of 23 s at 30 qC, calculated according to MILL and TUTTOBELLO (1961). One relative viscosimetric unit was defined as the amount of enzyme which reduced the initial viscosity of pectin solution by 50% in 1 minute of reaction.…”

Pectinase production profile of Aspergillus foetidus in solid state cultures at different acidities

“…Total pectinase activity (TPA) was determined at 30°C by following the kinetics of the viscosity drop (Mill and Tuttobello, 1961) using a polynomial regression program. The assay mixture consisted of 1 mL, of 0.2 N AcB, pH 4.0, containing 2.5 % apple pectin and 1 % of NaCl and 4 mL of an adequate dilution of the SA.…”