Purification and properties of polygalacturonic acid trans-eliminase from Bacillus stearothermophilus

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Abstract
A strain of thermophilic bacteria, B. stearothermophilus, with pectolytic activity has been isolated. It produced an endo-polygalacturonic acid trans-eliminase (endo-PATE, EC 4.2.2.1) extracellularly when grown at 65.degree. C on a pectic acid medium. The PATE was purified 62-fold by the rapid affinity chromatographic method on a Sepharose-polygalacturonamide linked matrix. The absorbed PATE was eluted from the column with a continuous gradient of 0-10-3 M EDTA in phosphate buffer at pH 7.6. The endo-PATE of this organism was much more heat stable than similar enzymes from the mesophilic B. polymyxa and the thermotolerant B. pumilus. The maximum activity of the enzyme occurred at 70.degree. C. With pectic acid as the substrate, the endo-PATE had an optimal pH of 9.0, the highest optimal pH compared with those of similar enzymes from other species of the genus. The MW of the endo-PATE, as determined by chromatography on a Sephadex G-100 gel column, was 24,000.