D- aldose family

Figure 16-19 shows the structures of all members of the D-aldose family. The circle (head) represents the aldehyde, and the lines to the left or right indicate the orientation of the -OH on each of the chiral carbon atoms. The bottom carbon atom is an achiral -CH2OH. (Note that the mirror image of each aldose in Figure 16-19 is the L-enantiomer.)... 

Fig. 1. The family of D-aldoses derive from D-glyceraldehyde by chain extension at the carbonyl carbon atom.

FIGURE 1.3 The family tree of D-aldoses with the trivial and abbreviated names. 

To continue forming the family of D-aldoses, we must add another carbon atom (bonded to H and OH) just below the carbonyl of either tetrose. Because there are two D-aldotetroses to begin with, and there are two ways to place the new OH (right or left), there are now four D-aldopentoses D-ribose, D-arabinose, D-xylose, and D-lyxose. Each aldopentose now has three stereogenic centers, so there are 2 = 8 possible stereoisomers, or four pairs of enantiomers. The D-enantiomer of each pair is shown in Figure 27.4. 

The family of D-aldoses having three to six carbon atoms... 

Most monosaccharides are aldoses, and almost all natural monosaccharides belong to the D series. The family of d aldoses is shown in I Figure 7.8. D-glyceraldehyde, the smallest monosaccharide with a chiral carbon, is the standard on which the whole series is based. Notice that the bottom chiral carbon in each compound is directed to the right. The 2" formula tells us there must be 2 trioses, 4 tetroses, 8 pentoses, and 16 hexoses. Half of those are the d compounds shown in Figure 7.8. The other half (not shown) are the enantiomers or l compounds. 

A family tree of the D-aldoses that have between three and six carbon atoms. 

Aldose sugars make up a large part of the carbohydrate family, but the ones that are really worth knowing are part of the D-family. The simplest of these D-sugars is the triose glyceraldehyde. From there you have 2 tetroses, 4 pentoses, and 8 hexoses. Each of these aldose sugars has an enantiomer. 

Wood-degrading fungi produce a family of pyranose oxidases (EC 1.1.3.10), enzymes catalyzing the oxidation at C-2 of several aldoses. A simple and convenient conversion of D-glucose into D-arabino-hexos-2-ulose involves the use of a pyranose-2-oxidase isolated from Polyporus obtusus, which was purified and immobilized on activated CH-Sepharose 4B.446... 

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