Abstract
The galactanase of Rhizopus niveus was extracted from koji culture, and separated into four fractions, F-I, F-II, F-III and F-IV, by the gel filtration on Sephadex G-100. These galactanases hydrolyzed coffee arabinogalactan. The extract also contained a β-galactosidase, which was separated from the galactanases by the gel filtration. The mannanase activity found in F-III and F-IV was removed by DEAE-Sephadex column chromatography of by mannan adsorption.
The pH optimum of these galactanases was about 5.0, and the pH stabilities were 3.0_??_9.0 for F-I, 3.0_??_6.5 for F-II, 3.0_??_7.5 for F-III and 3.0_??_8.0 for F-IV. The enzymes were all inactivated at temperatures above 50°C.
The degrees of hydrolysis of coffee arabinogalactan by the galactanases were in the order of F-I>F-II>F-III>F-IV. Whereas the solubilizing activities of the enzyme upon the insoluble arabinogalactan which contained a relatively large amount of mannose were in the order of F-IV>F-III>F-II>F-I.
