澱粉の結合リン酸とアミラーゼ作用
1987 年 34 巻 3 号 p. 225-233
詳細
1987 年 34 巻 3 号 p. 225-233
The actions of amylases in the vicinity of the phosphate groups at C-3 and C-6 of the glucosyl residues of potato starch and the locations of the phosphate groups in the starch, which were determined by analyses of the phosphorylated products, were summarized.
Sweet potato β-amylase and Aspergillus niger glucoamylase cleaved the (1→4)-α-D-linkage of the 6-phosphorylated residue at the non-reducing side but not that of the 3-phosphorylated one, leaving at least one glucosyl residue attached to the 3-phosphorylated one. α-Amylases from various origins cleaved different sites in the vicinity of the 3- and 6-phosphorylated residues, that is, the enzymes from Bacillus subtilis, porcine pancreas and Aspergillus oryzae produced 32-phosphoryl maltotetraose (32-PG4) and 62-phosphoryl maltotriose (62-PG3), 32-PG4 and 63-phosphoryl maltotriose (63-PG3), and 32-PG4 and 63-PG3, respectively, upon exhaustive hydrolysis. The phosphate group at C-6 was as obstructive as the branch linkage of amylopectin, but less obstructive than the phosphate group at C-3. Their inhibitory behavior seemed to reflect a bulk rather than an electronegative effect.
Most phosphate groups were found in the amylopectin fraction. The results of analyses of phosphorylatedbranched- and unbranched-chains produced from potato amylopectin on exhaustive β-amylolysis followed by isoamylolysis indicated that the phosphate groups were located mostly in B-chains (chains with side chains) and largely on the outer section of chains of amylopectin, except in the vicinity of the branch linkages.
