Degradation of elsinan by alpha amylases, and elucidation of its fine structure

✍ Scribed by Akira Misaki; Hisako Nishio; Yoichi Tsumuraya

• Publisher: Elsevier Science
• Year: 1982
• Tongue: English
• Weight: 903 KB
• Volume: 109
• Category: Article
• ISSN: 0008-6215
• DOI: 10.1016/0008-6215(82)84039-1

✦ Synopsis

Elsinan, a unique fungal polysaccharide consisting of maltotriose and maltotetraose units joined by a-D-(l-+3)-glucosidic linkages, was previously found to be degraded by particular types of alpha amylases, e.g., salivary, pancreatic, and bacterial (saccharifying) alpha amylase, to produce 0-a-D-glucosyl-( l-+3)-o-cc-D-gh_rcosyl-(i-4)-o-glucose as the major product. Taka amylase (alpha amylase of Aspergilh oryzae) is also capable of hydrolyzing elsinan, by cleaving cc-D-(l-+4)-glucosidic linkages in the maltotetraose units, but not in the maltotriose units, to produce several novel oligosaccharides. Methylation, and chemical and enzymic fragmentationanalyses, showed that the tetrasaccharide (TG,), as the major product, is O-X-Dglucosyl-(1 +3)-0-IX-D-glucosyl-(1 -+4)-O-cc-D-glucosyl-(l-+4)-D-glucose, and the heptasaccharide (TG,) has the sequence X-D-Glcp-( 1 -+3)-cc-D-Glcp-( 144)~cr-D-Glcp-(1 +4)-a-D-Glcp-( 1 + 3)-cr-D-Glcp-( I +4)-a-~-C&p-( 1 +I)-D-Glcp. The molar ratios of tetra-, hepta-, deca-, trideca-, and hexadeca-gluco-oligosaccharide released from elsinan by digestion with Taka amylase were estimated by gel-filtration chromatography to be 2.78 : 1 .O : 0.61: 0.26 : 0.11. The high-molecular weight saccharide of d.p. 30-35 (recovered in 33 % yield) in the enzyme digest consisted exclusively of M-D-(1+3)-linked maltotriose units. On the basis of the quantitation of these degradation products, the fine structure of elsinan and the substrate specificities of alpha amylases are discussed. *Dedicated to Professor Sumio Umezawa on the occasion of his 73rd birthday and the 25th anniversary of the Microbial Chemistry Research Foundation. **To whom requests for reprints should be addressed.