Purification and properties of two galactanases from Penicillium citrinum.

Abstract

Two galactanases (I and II) were purified to homogeneous states from water extracts of a wheat bran culture of Penicillium citrinum. Although these enzymes were separable by affinity chromatography and distinct on Polyacrylamide gel electrophoresis, they were similar in physical and enzymatic nature. They had almost the same molecular weight (3.5 } 104) and isoelectric point (pH 4.2), and similar amino acid compositions and carbohydrate contents (3%). Alanine and leucine were detected for both enzymes as the N- and C-terminal amino acids, respectively.These enzymes were most active at pH 4.5 and 55%C, and were stable between pH 4 and 10 (at 15%C for 24hr), and below 55%C (at pH 5.5 for 10min). The enzymes hydrolyzed soybean arabinogalactan to produce galactose and several galac-tooligosaccharides, but did not attack coffee bean arabinogalactan. Therefore, these enzymes were suggested to be endo-l,4-²-D-galactanases.The enzymes also attacked ONPG and PNPG, and lag phases were observed at the beginning of t...