Disaccharide type

Type-1 fucosylated Lewis disaccharide Type-1 Lewis A... 

Among the various types of sugars marketed, the mass consumption of sucrose far outweighs by volume the consumption of other products. Sucrose, also called table sugar, is a disaccharide which, upon hydrolysis, yields two monosaccharides glucose and fmctose. Various types of sugar vary in sweetness (1). 

In 1967, Heidelberger, Stacey et al. reported the purification, some structural features, and the chemical modification of the capsular polysaccharide from Pneumococcus Type I. Difficulties of direct hydrolysis of the polysaccharide were overcome and it was possible to identify some of the fragments in the hy-drolyzate. At least six products resulted from nitrous acid deamination. Two were disaccharides, which were identified, and sequences of linked sugar units were proposed. As modification of the polysaccharide decreased the amounts of antibody precipitated by anti-pneumococcal Type I sera, the importance of the unmodified structural features in contributing to the specificity of the polysaccharide was indicated. 

In contrast with the monotonous monosaccharide repeat and the same type of linkage in the polysaccharide structures (1 to 21) described in Sections IV and V, this section deals with rather more complex polymers (23 to 39), which are composed of disaccharide repeats. Further, combining two types of linkages enhances the formation of exotic morphologies not amenable to the former set. The sequence listed in Table II is referred to as -A-B- in Table V while listing... 

The cell walls of the Solanaceae plant species contain the XXGG type of XGs [247,275]. Suspension-cultured tobacco cells secrete a XG, bearing disaccharide side chains (11) [276], as similarly reported for XGs of other solana-ceous plants. The XG from suspension-cultured tomato cells is more complex, as it also contains the unusual / -L-Ara/-(1 3)-o -L-Ara/-(1 2)-a-D-Xylp trisaccharide side-chain (12) in addition to the prevaiUng dimeric moiety (13) [277]. 

As shown in Figure 48-8, the keratan sulfates consist of repeating Gal-GlcNAc disaccharide units containing sulfate attached to the 6 position of GlcNAc or occasionally of Gal. Type 1 is abundant in cornea, and type II is found along with chondroitin sulfate attached to hyaluronic acid in loose connective tissue. Types I and II have different attachments to protein (Figure 48—8). 

Figure 5. Acetylated RG-I helices generated from the low-energy conformations of the disaccharides (see Figures 2 and 3). Left the AA type with n = -3 and h = 6.75 A right the AB type with n = 2 and h = 7.48 A.

An early report from Shukla et al.129 showed efficient hydrolysis and isomerization reactions of disaccharides, including cellobiose, maltose, and lactose, over zeolites type A, X, and Y. Abbadi et al.130 studied the hydrolysis of maltose, amylose, and starch over the zeolitic materials H-mordenite, H-beta, and mesoporous MCM-41. The effect of temperature and pressure, as well as that of the Si/Al ratio of H-mordenite and H-beta zeolites, on their catalytic activity was investigated for the... 

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