Abstract
1. The A-decomposing enzyme preparation purified from a culture filtrate of Clostridium tertium has an ability to destroy the A activity of human A blood group substance, releasing from it galactose, N-acetylgalactosamine, N-acetylglucosamine, and N-acetylmannosamine as simple sugar as well as a disaccharide which is presumed to be N-acetylgalactosaminoyl- (1→3) -D-galactose. Thus, the enzyme preparation contains a type of β-D-galactosidase which liberates from A substance galactose and galactose-containing disaccharide, and also N-acetylhexosaminidase (s) which liberates N-acetylhexosamines.It is considered from these results that the component sugar of A substance derived from human gastric linings consits of L-fucose, D-galactose and in addition, aminosugars such as N-acetylgalactosamine, N-acetylglucosamine, and N-acetylmannosamine.
2. It is deduced that the B-decomposing enzyme preparation purified from a culture filtrate of Clostridium maebashi destroys the B activity of human B blood group substance to release from it D-galactose, non-reducing end galactosyl residue combined with second sugar probably through α-1→6 or 1→3 linkage. The enzyme preparation contains an enzyme which would be nominated B-decomposingα-D-galactosidase, because of failure to release any component sugar of B substarce except D-galactose and also to hydrolyze α-linked D-galactose-containing oligosaccharides such as melibiose, stachyose, and verbascose.
