1887

Abstract

The production of pectinase was studied in , using the hyperproducer mutant , which synthesized and secreted five to six times more enzyme than the wild-type. Polygalacturonase, pectin lyase and pectate lyase were induced by pectin, and this induction was glucose-repressible. Polygalacturonase was induced by galactose four times more efficiently than by pectin; in contrast the activity of lyases was not affected by galactose. The inducing effect of galactose on polygalacturonase was not glucose-repressible. Extracellular pectinases were separated by ion exchange chromatography. Pectate and pectin lyases eluted into three main fractions containing both activities; polygalacturonase eluted as a single, symmetrical peak, apparently free of other protein contaminants, and was purified 56-fold. The purified polygalacturonase was a monomeric glycoprotein (38% carbohydrate content) of apparent molecular mass 36.6-37.0 kDa (Sephadex G-100 and urea-SDS-PAGE, respectively). The enzyme hydrolysed predominantly polypectate. Pectin was also hydrolysed, but at 7% of the rate for polypectate. and V for polypectate hydrolysis were 5.0 mg ml and 357 µmol min (mg protein), respectively. Temperature and pH optima were 45°C and 6°0, respectively. The purified polygalacturonase reduced the viscosity of a sodium polypectate solution by 50%, with an increase of 7% in reducing sugar groups. The products of hydrolysis at initial reaction times consisted of oligogalacturonates without detectable monomer. Thus, the purified enzyme was classified as an endopolygalacturonase [poly(1,4-α-D-galacturonide) glycanohydrolase; EC 3.2.1.15].

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/content/journal/micro/10.1099/00221287-137-8-1815
1991-08-01
2019-10-15
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http://instance.metastore.ingenta.com/content/journal/micro/10.1099/00221287-137-8-1815
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