Chemical synthesis of a dual branched malto-decaose: a potential substrate for alpha-amylases.
A convergent block strategy for general use in efficient synthesis of complex alpha-(1-->4)- and alpha-(1-->6)-malto-oligosaccharides is demonstrated with the first chemical synthesis of a malto-oligosaccharide, the decasaccharide 6,6''''-bis(alpha-maltosyl)-maltohexaose, with two branch points. Using this chemically defined branched oligosaccharide as a substrate, the cleavage pattern of seven different alpha-amylases were investigated. Alpha-amylases from human saliva, porcine pancreas, barley alpha-amylase 2 and recombinant barley alpha-amylase 1 all hydrolysed the decasaccharide selectively. This resulted in a branched hexasaccharide and a branched tetrasaccharide. Alpha-amylases from Asperagillus oryzae, Bacillus licheniformis and Bacillus sp. cleaved the decasaccharide at two distinct sites, either producing two branched pentasaccharides, or a branched hexasaccharide and a branched tetrasaccharide. In addition, the enzymes were tested on the single-branched octasaccharide 6-alpha-maltosyl-maltohexaose, which was prepared from 6,6''''-bis(alpha-maltosyl)-maltohexaose by treatment with malt limit dextrinase. A similar cleavage pattern to that found for the corresponding linear malto-oligosaccharide substrate was observed.
The Carbohydrate Chemistry Group, Plant Biochemistry Laboratory, Department of Plant Biology and Center for Molecular Plant Physiology, The Royal Veterinary and Agricultural University, 1871 Frederiksberg C, Copenhagen, Denmark.
Iben
I
Damager
Morten T
MT
Jensen
Carl E
CE
Olsen
Andreas
A
Blennow
Birger L
BL
Møller
Birte
B
Svensson
Mohammed S
MS
Motawia
D002240:Carbohydrate Sequence; D002853:Chromatography, Liquid; D007527:Isoenzymes / Q000378:metabolism; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000138:chemical synthesis* / Q000737:chemistry / Q000378:metabolism*; D000516:alpha-Amylases / Q000378:metabolism*
D007527:Isoenzymes; D009844:Oligosaccharides; C021705:maltooligosaccharides; D000516:alpha-Amylases