Actions of porcine pancreatic and Bacillus subtilis alpha-amylases and Aspergillus niger glucoamylase on phosphorylated (1--4)-alpha-D-glucan.

Porcine pancreatic alpha-amylase (1,4-alpha-D-glucan glucanohydrolase, EC 3.2.1.1) produced O-6-phosphoryl-alpha-D-glucopyranosyl-(1--4)-O-alpha-D-glucopyranosyl -(1--4)-D-glucopyranose (6(3)-phosphoryl maltotriose) and O-alpha-D-glucopyranosyl-(1--4)-O-alpha-D-glucopyranosyl- O-3-phosphoryl-alpha-D-glucopyranosyl-(1--4)-D-glucopyranose (3(2)-phosphoryl maltotetraose) from potato starch upon exhaustive hydrolysis, while Bacillus subtilis alpha-amylase (liquefying type) yielded O-alpha-D-glucopyranosyl-(1--4)-O-6-phosphoryl-alpha-D- -glucopyranosyl-(1--4)-D-glucopyranose (6(2)-phosphoryl maltotriose) and 3(2)-phosphoryl maltotetraose. Thus, the two alpha-amylases cleave different sites in the vicinity of the phosphate group at C-6 of the glucosyl residue but the same site in the vicinity of that at C-3. Aspergillus niger glucoamylase (1,4-alpha-D-glucan glucohydrolase, EC 3.2.1.3) hydrolyzed the (1--4)-alpha-linkage of the 6-phosphoryl residue at the non-reducing site (Abe, J., Takeda, Y. and Hizukuri, S. (1982) Biochim. Biophys. Acta 703, 26-33) but not that of the 3-phosphoryl residue, leaving a glucosyl residue attached to the 3-phosphoryl residue. These results indicate that the phosphate group at C-3 is more obstructive than that at C-6 for the actions of these three amylases.