Two-step enzymatic synthesis of maltooligosaccharide esters

Area of Science:

• Biocatalysis
• Enzymology
• Carbohydrate Chemistry

Background:

• Enzymatic synthesis offers a green chemistry approach for producing functionalized carbohydrates.
• Lipases and glycosyltransferases are versatile biocatalysts for esterification and glycosylation reactions.

Purpose of the Study:

• To synthesize glucose and maltose esters using enzymatic methods.
• To extend the degree of polymerization (DP) of carbohydrate moieties in esters via transglycosylation.
• To identify optimal substrates for efficient maltooligosaccharide ester formation.

Main Methods:

• Enzymatic synthesis of glucose and maltose esters using Candida antarctica lipase.
• Transglycosylation reactions catalyzed by cyclodextrin glycosyltransferases (from Paenibacillus sp. F8 or Bacillus sp. strain no. 169).
• Utilized cyclodextrins, maltooligosaccharides, or starch as glycosyl donors.
• Characterization of product structures using NMR spectroscopy and MALDI-TOF MS.

Main Results:

• Successful synthesis of carbohydrate esters with extended DP.
• Identified starch as the optimal glycosyl donor and caproyl maltose as the optimal glycosyl acceptor for low DP maltooligosaccharide ester formation.
• Determined the structures of capronate monoesters of maltotriose and maltotetraose, with ester linkage at C-6 of the second glucose unit from the reducing end.

Conclusions:

• Enzymatic cascade reactions enable the synthesis of complex carbohydrate esters.
• The choice of glycosyl donor and acceptor significantly impacts the efficiency of maltooligosaccharide ester formation.
• Detailed structural elucidation confirms the regioselectivity of the enzymatic transglycosylation process.