885d_c07-238-27211/21/037:38 AM Page241Mac113mac113:1aEDL Chapter 7 Carbohydrates and Glycobiology 241 Four carbons Five carbons H O H 0 H O H O H-C-oH HO- H-C-oH HO-C-H H-C-oH H--C-OH HO H-C-OH H-C-OH H→C-OH H-C-OH H OH HoH OH D-Glyceraldehyde D-ErythroseD-Threose D-Ribose [D-Arabinose Xylo L Six carbons H O H O H 0 H O H O H H O H O H-C-OH o-C-H OHHo→-H HC- OH HO-C—H H-C-OH HO-C-H H--C-O H-C-oH HO-C-H HO→C-H H-C-oHH-C-oh HO-C-H HO-C-H H-C-ohH-C-oh H-C-oh H-C-oh HO--C-H Ho--C-h Ho--c-h Ho-C-H OH H-C-oH H-C-oH H-C-oH H-C-oH H-C-oH D-Glucose D-Mannose D-Gulose D-Idose D-Galactose DAldoses Three carbons our carbons FIGURE 7-3 Aldoses and ketoses. The series of (a)D-aldoses and (b)Ketoses having from three to six carbon atoms, shown as CH2OH projection formulas. The carbon atoms in red are chiral centers. In all these D isomers, the chiral carbon most distant from the carbonyl carbon has the same configuration as the chiral carbon OH in D-glyceraldehyde. The sugars named in boxes are the most Dihydroxyacetone common in nature; you will encounter these again in this and Five carbons Six carbons CHOH CHoO CHOO C=0 H-C-OH O-C-H H-C-OH H-C-OH H-C-OH -C-OH D-Ribulose cho CHO H-C-OH H-C-OHI CHoO CHoO HO-°C-H CH,OH C-O H-C-OH HOC—H C=O HO-C-H H-C-OH HOH D-Glucose D-Galactose CH2OH CH2OH at C-2) (epimer at C-4) D-Xylulose D-Sorbose FIGURE 7-4 Epimers. D-Glucose and two of its epimers are shown D-Ketoses as projection formulas. Each epimer differs from D-glucose in the con figuration at one chiral center(shaded red)Chapter 7 Carbohydrates and Glycobiology 241 D-Aldoses (a) Six carbons Three carbons H O C H C OH CH2OH D-Ribose H C OH H OH C H C O OH CH2OH D-Glyceraldehyde H C C H O CH2OH D-Threose C H C OH HO H H C O OH CH2OH D-Erythrose H C H C OH H C O OH CH2OH D-Allose C H C OH H OH C H C OH H HO C H CH2OH D-Lyxose H C OH C H HO H O C H C OH CH2OH D-Xylose H C OH HO C H H O C C H CH2OH D-Arabinose H C OH H OH C HO H O C C H CH2OH D-Talose H C OH C H C H HO HO HO H O C H C OH CH2OH D-Gulose H C OH C H H C OH HO H O C HO C H CH2OH D-Mannose H C H C OH C H OH HO H O C H C OH CH2OH D-Glucose H C OH H OH C HO C H H O C Four carbons C H CH2OH D-Idose H C OH C H H C OH HO HO H O C H C OH CH2OH D-Galactose H C OH C H HO C H HO H O C C H CH2OH D-Altrose H C OH H OH C H C OH HO O C H Five carbons D-Ketoses (b) H OH O D-Ribulose CH2OH C CH2OH C H C OH H OH O D-Psicose CH2OH C CH2OH C H C OH H C OH HO H O D-Fructose CH2OH C CH2OH C H C OH H C OH H O D-Tagatose CH2OH C CH2OH C H C OH C H HO HO O D-Sorbose CH2OH C CH2OH C OH H C C H HO OH H Dihydroxyacetone CH2OH C CH2OH O Three carbons Five carbons Six carbons Four carbons O D-Xylulose CH2OH C CH2OH C OH H H C HO H OH O D-Erythrulose CH2OH C CH2OH C FIGURE 7–3 Aldoses and ketoses. The series of (a) D-aldoses and (b) D-ketoses having from three to six carbon atoms, shown as projection formulas. The carbon atoms in red are chiral centers. In all these D isomers, the chiral carbon most distant from the carbonyl carbon has the same configuration as the chiral carbon in D-glyceraldehyde. The sugars named in boxes are the most common in nature; you will encounter these again in this and later chapters. H C OH CH2OH D-Mannose (epimer at C-2) C HO C H C CHO 6 1 2 3 4 5 H C OH CH2OH D-Glucose H C HO C H OH H C OH CHO 6 1 2 3 4 5 H C OH CH2OH D-Galactose (epimer at C-4) H C HO C H OH C CHO 6 1 2 3 4 5 H OH HO H HO H FIGURE 7–4 Epimers. D-Glucose and two of its epimers are shown as projection formulas. Each epimer differs from D-glucose in the con￾figuration at one chiral center (shaded red). 8885d_c07_238-272 11/21/03 7:38 AM Page 241 Mac113 mac113:122_EDL: