الفهرس 
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Abstract
Cyclomaltodextrin glucanotransferase (CGT’ase, EC 2.4.1.19) is an unique enzyme which has the ability to convert starch to cyclodextrins. Alpha-amylases and cyclomaltodextrin glucanotransferases (CGT’ase) are able to cleave a-1,4-glucosidic bonds within the molecules of amylose and starch. The hydrolysis products from the substrates by a-amylases include glucose, maltose and maltooligosaccharides. In contrast, CGT’ases degrade the substrates mainly to cyclodextrins, in which six to eight glucose units are joined by means of a-1,4-glucosidic bonds (French, 1957; Pulley and French, 1961; Kobayashi et al, 1978; Matsuzaki et al, 1974). Thus the a-1- 4-glucosidic bonds can be reformed through the activity of CGT’ase, in addition to being initially cleaved by its amylase activity. According to the number of glucose units (G, G, and Gg) forming the cyclodextrins, they are named alpha, beta, and gamma-cyclodextrins, respectively. These are the most common types of cyclodextrins.
Cyclodextrins are crystalline cyclic oligosaccharides, which mainly form a doughnut or torus shape (Bender and Komiyama, 1978). The interrior of the cyclodextrin molecules is relatively apolar compared to water. Thereby, these cyclic oligosaccharides are capable of forming inclusion complexes with a wide variety of inorganic and organic chemical compounds, by incorporating them into the hydrophobic cavities of their molecules. This unique phenomenon, known as ”molecular encapsulation”, could improve the apparent physical and chemical properties of the ”guest” molecules. Consequently, considerable interest has been generated and rapidly increased recently to commercially exploit cyclodextrins.