Carbohydrate Analysis Experiment Involving Mono- and Disaccharides with a Twist of Glycobiology: Two New Tests for Distinguishing Pentoses and Glycosidic Bonds

Carbohydrate analysis is an excellent way to expose second-year biochemistry majors to the subtlety and nuance of sugar chemistry. In one, 3-h practical period, students must identify an unknown mono- or disaccharide from a collection of three hexoses (glucose, galactose, and mannose), two pentoses (ribose and arabinose), and three disaccharides (maltose, cellobiose, and lactose). Two new tests have been developed: an enzyme assay with α-glucosidase followed by the Barfoed test quickly distinguishes maltose and cellobiose and 1,1-diphenylhydrazine is used to identify arabinose. The exercise is presented as a way to sensitize new students of biochemistry to the communicative aspect of sugars.