Isomaltose is a disaccharide that can be obtained by enzymatic hydrolysis of amylopectin. Deduce the structure of isomaltose from the following data:
1. Hydrolysis of 1 mol of isomaltose by acid or by an α-glucosidase gives 2 mol of D-glucose.
2. Isomaltose is a reducing sugar.
3. Isomaltose is oxidized by bromine water to isomaltonic acid. Methylation of isomaltonic acid and subsequent hydrolysis yields 2, 3, 4, 6-tetra-O-methyl-d-glucose and 2, 3, 4, 5-tetra-O-methyl-d-gluconic acid.
4. Methylation of isomaltose itself followed by hydrolysis gives 2, 3, 4, 6-tetra-O-methyl-d-glucose and 2, 3, 4-tri-O-methyl-d-glucose.