N- Acetyl sugars

NaBH4 (sodium borohydride), 732 N-Acetyl sugars, colorimetric quantification, 656, 658... 

Fig. 1. The chemical structure of chi tin and chitosan, a copolymer of the N-acetyl sugar and the amino sugar. Chi tin occurs as mostly the x or N-acetyl form. Chitosan occurs as the y or amino form.

Kawagishi, H., Yamawaki, M., Isobe, S., Usui, T., Kimura, A., and Chiba, S., 1994, Two lectins from the marine sponge Halichondria akadai An N-acetyl-sugar-specific lectin (HOL-I) and an N-acetyllactosamine-specific lectin (HOL-II). J. Biol Chem. 269 1375-1379. 

Another structural variation is the replacement of a hydroxyl group m a carbohydrate by an ammo group to give an ammo sugar The most abundant ammo sugar is one of the oldest and most abundant organic compounds on earth N Acetyl d glucosamine is the... 

Amino sugars, such as o-glucosamine, have an OH group leplaced by an -NH2. The N-acetyl amide derived from o-glucosamine is the monosaccharide unit from which chitm, the hard crust that protects insects and shellfish, is made. Still otheramino sugars are found in antibiotics such as streptomycin and gentamicin. 

N-Acetylneur-aminic acid Sialic acid (nine C atoms) NeuAc CMP-NeuAc Often the terminal sugar in both N- and 0-linked glycoproteins. Other types of sialic acid are also found, but NeuAc is the major species found in humans. Acetyl groups may also occur as 0-acetyl species as well as N-acetyl. 

Alkaline conditions are used so frequently in carbohydrate separations on CarboPac columns that it should be pointed out that acidic conditions are suitable for separation of acidic sugars. Figure 24 shows the separation of sialic acid containing oligosaccharides.256 Alkaline conditions were used for neutral milk oligosaccharides and mucin oligosaccharide alditols were characterized similarly.257 The carbohydrates released from yeast mannopro-tein with N-acetyl-P-D-glucosaminidase were also fractionated on CarboPac ... 

The amino sugar counterparts of D-glucuronic acid and nonsulfated L-iduronic acid in heparin are either N-acetylated, or nonsulfated at C-6, or both. 2-Acetamido-2-deoxy-D-glucosyl residues account for only a minor proportion of the total hexosamine in heparin, and are especially low in beef-lung preparations (see Table II).8,138,147 -149 In contrast, they... 

It will be appropriate to consider first the building units of the carbohydrate residues and it will be immediately apparent that D-mannose and D-galactose with N-acetyl-amino sugars and hexuronic acids play a predominant role. It is proposed, therefore, to discuss briefly some of the more important discoveries connected with the two latter groups and with the carbohydrate sulfates. 

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