Cyclic amyloses

To date the chiral host molecules most frequently used are the cyclic amylose oligomers or cyclodextrins (Cy), and the work in homogeneous solutions parallels the work done where they are used as chiral stationary phases [5,27], Among the major reasons for the choice are the ready availability of the compounds in relatively high chemical and optical purity and the convenience of the complexation reactions ... 

Cyclodextrins, on the other hand, are used extensively in cosmetic and drug delivery applications (132-136). Cyclodextrins, as the name implies, are cyclic amyloses comprised of 6 (a-), 7 (P-), and 8 (y-), a-D-(l,4)-glucose monosaccharides (Fig. 30). Their small size classifies them as oligo- instead of polysaccharides, which places them somewhat outside the scope of this chapter. Nevertheless, cyclodextrins are important components in many cosmetic formulations where they function as hosts and solubilizing agents for water-sensitive or water-insoluble materials. 

AMR See aminomethyl propanol, cyclic aminomethyl propanol AMP-95. See aminomethyl propanol amphetamines, 160 amyl p-methoxy cinnamate, 5 amylase, 87, 155 amylopectin, 144-145 amylose, 31-32, 144-145, 152 analgesics. See pain relievers anesthesin. See benzocaine anesthetics, 60, 172-175, 229 annatto, 105-106, 107, 114, 117 antacids, 169 anthocyanins, 109-111 antibacterials, 13, 25, 26,42, 67, 86,... 

Carboxymethyl Amylose Medium Induced Medium Rigid Cyclic Side Chain Strong... 

These water-soluble molecules are cyclic oligomers of a-D-glucose formed by the action of certain bacterial amylases on starches (Bender and Komiyama, 1978 Saenger, 1980 Szejtli, 1982). a-Cyclodextrin (cyclohexa-amylose) has six glucose units joined a(l, 4) in a torus [1], whereas /3-cyclodextrin (cycloheptaamylose) and y-cyclodextrin (cyclooctaamylose) have seven and eight units, respectively. 

Cyclodextrins (sometimes called cycloamyloses) make up a family of cyclic oligosaccharides composed of 5 or more a-D-glucopyranoside units linked 1 —> 4, as in amylose (a fragment of starch), and have been used as activating macrocyclic excipients in nonaqueous biocatalysis. Griebenow et al. observed that lyophilization of methyl-[3-cyclodextrin with subtilisin Carlsberg in a 6 1 weight ratio resulted in a 164-fold rate enhancement in THF for the transesterification rate of sec-phenethyl alcohol with vinyl butyrate (Scheme 3.3) [98]. 

We have tested various 4aGTs for their ability to produce cyclic a-1,4 glucan from amylose, and now have the view believe that a cyclization reaction is the common feature of this enzyme (Fujii et al., 2003 Yanase et al., 2002). However, the smallest cyclic glucan produced is greatly dependent on the type of enzyme employed (Table 28.2). In addition to two transferase activities described above, some 4aGTs also exhibit week hydrolitic activity (Fujii et al., 2005a). 

As described, cyclic a-1,4 glucan can be produced by the cyclization reaction of 4aGTs on amylose. The smallest cyclic glucan produced is dependent on the type of enzyme employed (Table 28.3). Yield of cyclic glucan appeared to... 

Takaha,T., Yanase, M.,Takata, FI., Okada, S., and Smith, S. M. 1996. Potato D-enzyme catalyzes the cyclization reaction of amylose to produce cycloamylose, a novel cyclic glucan. J. Biol. Chem., 271,2902-2908. 

The branching enzyme from Bacillus stearomophilus decreased the molecular size of synthetic amylose. On studying the product of this reaction, it was found that BE had catalyzed the intramolecular transglycosylation to form a cyclic structure with a side chain. After removing the cyclic part of the molecule (using isoamylase) from the rest of the molecule, its cyclic nature was confirmed by the use of mass spectrometry. The authors proposed a new mechanism for the action of BE and suggested that plant BE may catalyze the cyclization of amylose and amylopectin. 

P-Cyclodextrin Based on 7 glucopyranose units the a-form has only 6 units Amylose derived, cyclic heptasaccharide, capable of forming inclusion complexes of drugs Inclusion complexes with drugs to mask odor to taste... 

Cyclodextrins (cyclic hexa-, hepta-, octa-glucoses) from amylose (starch) Bacillus circulans, macerans... 

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