25.10 Some Other Important Carbohydrates
25.10 • Some Other Important Carbohydrates
In addition to the common carbohydrates mentioned in previous sections, there are a variety of important carbohydrate-derived materials. Their structural resemblance to sugars is clear, but they aren’t simple aldoses or ketoses.
Deoxy sugars, as we saw in Section 25.7, have an oxygen atom “missing.” That is, an –OH group is replaced by an –H. The most common deoxy sugar is 2-deoxyribose, a monosaccharide found in DNA (deoxyribonucleic acid). Note that 2-deoxyribose exists in water solution as a complex equilibrium mixture of both furanose and pyranose forms.
Amino sugars, such as D-glucosamine, have an –OH group replaced by an –NH2. The N-acetyl amide derived from D-glucosamine is the monosaccharide unit from which chitin, the hard crust that protects insects and shellfish, is made. Still other amino sugars are found in antibiotics such as streptomycin and gentamicin.