Chemical synthesis of methyl 6′-α-maltosyl-α-maltotrioside and its use for investigation of the action of starch synthase II

• Published in: Carbohydrate research Vol. 338; no. 2; pp. 189 - 197
• Main Authors: Damager, Iben, Olsen, Carl Erik, Blennow, Andreas, Denyer, Kay, Møller, Birger Lindberg, Motawia, Mohammed Saddik
• Format: Journal Article
• Language: English
• Published: OXFORD Elsevier Ltd 20.01.2003; Elsevier
• Subjects: Biochemistry & Molecular Biology; Carbohydrates; Catalysis; Chemistry; Chemistry, Applied; Chemistry, Organic; Disaccharides - chemical synthesis; Disaccharides - metabolism; Enzymes; Glucose - metabolism; Glycosylation; Life Sciences & Biomedicine; Magnetic Resonance Spectroscopy; Maltose - analogs & derivatives; Maltose - chemical synthesis; Maltose - metabolism; Methyl 6′-α-maltosyl-α-maltotrioside; Oligosaccharides - biosynthesis; Oligosaccharides - chemistry; Oligosaccharides - isolation & purification; Physical Sciences; Plant Proteins; Science & Technology; Starch Synthase - metabolism; Starch synthase II; Substrate Specificity; Trisaccharides - chemical synthesis; Trisaccharides - metabolism; Bicine, N,N-Bis(2-hydroxyethyl)glycine; Carbohydrates; Enzymes; Methyl 6′-α-maltosyl-α-maltotrioside; BSA, Bovine serum albumine; SBE, Starch branching enzyme; AGPase, ADPglucose pyrophosphorylase; Starch synthase II; LC–MS, Liquid Chromatography-Mass Spectrometry; Mops, 4-Morpholinepropanesulfonic acid; Glycosylation; DPM, Disintegrations per minute; HPAEC, High-performance anion-exchange chromatography; ADPG, Adenosine 5′-diphospho- d-glucose; PAD, Pulse amperometric detection; DTT, Dithiothreitol; EDTA, Ethylenediaminetetraacetate; SS, Starch synthase; ADP[U-14C]glucose, Adenosine 5′-diphospho-( d-glucose-UL-14C); DP, Degree of polymerisation; GBSS, Granule-bound starch synthase; MES, 2-[N-Morpholino]ethanesulfonic acid; carbohydrates; methyl 6 '-alpha-maltosyl-alpha-maltotrioside; starch synthase II; AMYLOPECTIN; PROTEIN; REDUCTION; enzymes; glycosylation; GRANULES
• ISSN: 0008-6215; 1873-426X
• DOI: 10.1016/S0008-6215(02)00410-X

The branched pentasaccharide methyl 6′-α-maltosyl-α-maltotrioside was chemically synthesised and investigated as a primer for particulate starch synthase II (SSII) using starch granules prepared from the low-amylose pea mutant lam as the enzyme source. For chemical synthesis, the trichloroacetimidate activation method was used to synthesise methyl O-(2,3,4,6-tetra- O-benzyl-α- d-glucopyranosyl)-(1→4)- O-(2,3,6-tri- O-benzyl-α- d-glucopyranosyl)-(1→6)- O-[(2,3,4,6-tetra- O-benzyl-α- d-glucopyranosyl-(1→4)]- O-(2,3-di- O-benzyl-α- d-glucopyranosyl)-(1→4)-2,3,6-tri- O-benzyl-α- d-glucopyranoside, which was then debenzylated to provide the desired branched pentasaccharide methyl 6′-α-maltosyl-α-maltotrioside as documented by 1H and 13C NMR spectroscopy. Using a large excess of the maltoside, the pentasaccharide was tested as a substrate for starch synthase II (SSII). Both of the non-reducing ends of methyl 6′-α-maltosyl-α-maltotrioside were extended equally resulting in two hexasaccharide products in nearly equal amounts. Thus, SSII catalyses an equimolar and non-processive elongation reaction of this substrate. Accordingly, the presence of the α-1,6 linkages does not dictate a specific structure of the pentasaccharide in which only one of the two non-reducing ends are available for extension. Graphic