ABSTRACT
Catalyzed Polymerization Apparent production of an enzymatically synthesized amylose in DMSO was carried out by means of the calcium alginate hydrogel beads/DMSO system as the reaction field of the phosphorylase-catalyzed polymerization (Fig. 4.2) [8]. When the calcium alginate hydrogel beads including Glc-1-P, maltoheptaose, and phosphorylase were suspended in DMSO and the system was slowly stirred at 40°C for 12 h, the reaction proceeded to produce amylose, which eluted to the DMSO solution. The time-curse experiment in the system revealed that the enzymatic polymerization took place for 15 min on the inside of the calcium alginate beads and the produced amylose gradually eluted to the surrounding DMSO solution. One of the significant characteristics in the phosphorylase-cata-lyzed polymerization is to initiate the reaction from a nonreducing end of the primer [9]. Therefore, the modified primers can be used for the phosphorylase-catalyzed polymerization to introduce the functional groups at the chain end of amylose or maltooligosaccha-
rides. For example, the phosphorylase-catalyzed polymerization us-ing 2-chloro-4-nitrophenyl (CNP) β-maltopentaoside was performed to produce CNP-maltooligosaccharides with longer chain lengths of DPs in the range 8-11 [10]. These maltooligosaccharide derivatives were indispensable tools in the study on the binding sites and the actions of α-amylases having longer binding area than that of human α-amylase. Glycogen is known as a high-molecular-weight and water-soluble polysaccharide, which is composed of linear chains containing an average of 10-14 (14)-linked α-glucose residues, interlinked by α-(16)-glycosidic linkages to form highly branched structure [11,12]. Besides glycogen being a substrate for the in vivo phosphorolysis by glycogen phosphorylase, it was used as a primer for the phosphorylase-catalyzed polymerization. When the phosphorylase-catalyzed polymerization of glycogen using Glc-1-P was carried out (Fig. 4.3a), followed by standing further at room temperature for 24 h, the reaction mixture turned into a hydrogel form (Fig. 4.3b) [13]. The hydrogelation was probably caused by the formation of junction zones based on the double helix structure of the elongated amylose chains among the glycogen molecules.
