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ARS Home » Research » Publications at this Location » Publication #120551
Title: ENZYMIC ALPHA-GALACTOSYLATION OF A CYCLIC GLUCOTETRASACCHARIDE DERIVED FROM ALTERNAN

Author
item BIELY, PETER - SLOVAK ACADEMY
item PUCHART, VLADIMIR - SLOVAK ACADEMY
item Cote, Gregory

Submitted to: Carbohydrate Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/26/2001
Publication Date: N/A
Citation: N/A

Interpretive Summary: Alternan is a water-soluble gum that is being considered as a replacement for imported gum arabic and as a low-calorie bulking agent in foods. While studying the microbial digestion of alternan, it was discovered that some of the products had unusual chemical structures. These products were found to be cyclic (ring-shaped) sugars, which is very unusual for compounds of this type. In order to expand the potential uses for this novel compound, we have developed a method of attaching a biologically active sugar unit to the ring structure. The method uses a mild enzyme treatment and a sugar derived from honey. The product is potentially useful in biological studies, and it can be further modified using specific enzymes. This research is of interest to other carbohydrate scientists and to immunologists.

Technical Abstract: Alternanase catalyzes the hydrolysis of alternan, an alpha-1,3-alpha- 1,6-D-glucan produced by Leuconostoc mesenteroides, resulting in the formation of a cyclic tetramer cyclo{-3)-alpha-D-Glcp-(1-6)-alpha-D- Glcp-(1-}2 (cGlc4). Two alpha-galactosidases, one from coffee bean and the other produced by a fungus, currently described as Thermomyces lanuginosus, were found to catalyze an efficient 6-O-alpha-D- galactopyranosylation of cGlc4. The attachment of a non-reducing alpha-D-galactopyranosyl residue to the cGlc4 molecule opens new possibilities for future applications of the cyclic tetramer, since the D-galactopyranosyl residue can be easily modified by D-galactose oxidase to introduce a reactive aldehyde group. The results also extend our knowledge about the synthetic potential of T. lanuginosus alpha-galactosidase.