Enzymatic synthesis, structure of isomalto/malto-polysaccharides from linear dextrins prepared by retrogradation.

Isomalto/malto-polysaccharides (IMMPs) with degree of polymerization (DP) 10-100 have novel potential applications, including enhanced solubility and anti-inflammatory. However, there are minimal synthetic methods for preparing IMMPs with a relatively higher DP, which is due to the lack of suitable molecular weight linear dextrins (I-LDs). The existing I-LDs preparation methods have disadvantages, such as low yield and uncontrollable molecular weight. Therefore, this study proposes a method for preparing soluble linear dextrins (S-LDs, Mw = 2.1 kDa) by low-temperature retrogradation from debranched waxy corn starch (Mw = 3.0 kDa). S-LDs reacted with 4,6-α-glucanotransferase GtfB-ΔN from Limosilactobacillus reuteri 121 to yield IMMPs with 12.3 kDa Mw and 83.8% α1 â†’ 6 linkages content. Process monitoring revealed the synthesis mechanism and a detailed reaction process. Finally, IMMPs were identified by enzyme fingerprinting as α1 â†’ 6 chains with α1 â†’ 4 fragments inlaid at the reducing, non-reducing end, and middle part. This study provides a new synthesis method and more structural information for IMMPs.

Structure, function and enzymatic synthesis of glucosaccharides assembled mainly by α1 → 6 linkages - A review.

A variety of glucosaccharides composed of glucosyl residues can be classified into α- and ß-type and have wide application in food and medicine areas. Among these glucosaccharides, ß-type, such as cellulose and α-type, such as starch and starch derivatives, both contain 1 â†’ 4 linkages and are well studied. Notably, in past decades also α1 â†’ 6 glucosaccharides obtained increasing attention for unique physiochemical and biological properties. Especially in recent years, α1 â†’ 6 glucosaccharides of different molecular weight distribution have been created and proved to be functional. However, compared to ß- type and α1 â†’ 4 glucosaccharides, only few articles provide a systematic overview of α1 â†’ 6 glucosaccharides. This motivated, the present first comprehensive review on structure, function and synthesis of these α1 â†’ 6 glucosaccharides, aiming both at improving understanding of traditional α1 â†’ 6 glucosaccharides, such as isomaltose, isomaltooligosaccharides and dextrans, and to draw the attention to newly explored α1 â†’ 6 glucosaccharides and their derivatives, such as cycloisomaltooligosaccharides, isomaltomegalosaccharides, and isomalto/malto-polysaccharides.