Acceptor specificity of 4-alpha-glucanotransferase from Pyrococcus kodakaraensis KOD1, and synthesis of cycloamylose

4-alpha -Glucanotransferase from a hyperthermophilic archaeon Pyrococcus ko dakaraensis KOD1 showed a broad acceptor specificity to various saccharides in an intermolecular transglycosylation reaction. In particular, the enzym e produced large amounts of transfer products of various accepters such as D-glucose, methyl-alpha -D-glucoside, phenyl-a-D-glucoside, and D-xylose. I t is suggested that the requirement for an effective acceptor in the interm olecular transglycosylation reaction catalyzed by this enzyme is the pyrano se structure with the same configurations of the free C2-, C3-, and C4-hydr oxyl groups as D-glucopyranose, like cyclomaltodextrin glucanotransferase ( CGTase). However, the enzyme showed some acceptor specificities unlike thos e of CGTase. Analysis of the action of 4-alpha -glucanotransferase indicate d that the enzyme catalyzes an intramolecular transglycosylation (cyclizati on) reaction of amylose to produce cyclic alpha -1,4-glucan (cycloamylose). The yield of cycloamylose reached 67%, and the degree of polymerization wa s found to range from 16 to above 55.