A blood group substance

Kabat, E. A. Blood-Group Substances. Their Chemistry and Immuno-... 

Isolation and Characterization of a Substance from Human Ovarian Cyst Fluid of a Blood Group Substance Lacking A, B, H, Lea, and Leb Specificity, J. Immunol (1969) 102,821. 

Ions of Mn2+ and Ca2+ were bound to the purified, lima-bean lectins.151,199 Removal of Mn2+ lowered the hemagglutination titer by 75%. (Ethylenedinitrilo)tetraacetate completely inhibited the precipitin reaction between lima-bean lectin component III and type A blood-group substance (compare Ref. 579). Several divalent-metal cations restored activity to the demetallized protein or (ethylenedinitrilo)tetraacetate-treated lectin the addition of Ca2+,... 

The reaction of partially purified, lima-bean lectin with hog gastric-mucin type A substance exemplified the precipitin-like curve obtained for lectin-polysaccharide or -glycoprotein reactions.103 Classical precipitin-curves between purified components II and III and type A blood-group substance were also obtained.151,199 Maximal precipitation of component II (equivalence) occurred at a lower ratio of A substance per mole of protein than for component III. Under conditions where type A substance precipitated 90% of the lectin, types A2 and B precipitated151,199 66 and 13%, respectively, of component II, and 21 and 0% of component III. Neither of the lima-bean lectins precipitated with type O blood-group substance. 

By the catalytic reduction of the phenylosazone from lactose, Kuhn and Kirschenlohr obtained both /3-n-gaIactopyranosyl-(l— 4)-l-amino-l-deoxy-D-fructose and /S-n-galactopyranosyl- (1- -4) -2-amino-2-deoxy-D-glu-cose. The A -acetyl derivative of the latter was found to be identical with a disaccharide obtained from the partial hydrolysis of a blood-group substance. The structure of a disaccharide obtained from the partial hydrolysis of heparin was likewise confirmed by comparison of the disaccharide with a synthetic product obtained by catalytic hydrogenation of the osazone from maltose. - Here, too, both the 1-amino-l-deoxy and the 2-amino-2-deoxy compounds were obtained. 

The ABO substances have been isolated and their structures determined simphfied versions, showing only their nonreducing ends, are presented in Figure 52—6. It is important to first appreciate the structure of the H substance, since it is the precursor of both the A and B substances and is the blood group substance found in persons of type O. H substance itself is formed by the action of a fiicosyltransferase, which catalyzes the addition of the terminal fiicose in al —> 2 linkage onto the terminal Gal residue of its precursor ... 

Figure 52-6. Diagrammatic representation of the structures of the H, A,and B blood group substances. R represents a long complex oligosaccharide chain, joined either to ceramide where the substances are glycosphingolipids, or to the polypeptide backbone of a protein via a serine or threonine residue where the substances are glycoproteins. Note that the blood group substances are biantenna ry ie, they have two arms, formed at a branch point (not indicated) between the GIcNAc—R, and only one arm of the branch is shown. Thus, the H, A,and B substances each contain two of their respective short oligosaccharide chains shown above. The AB substance contains one type A chain and one type B chain.

The ABO blood group substances in the red cell membrane are complex glycosphingohpids the immunodominant sugar of A substance is A -acetyl-galactosamine, whereas that of the B substance is galactose. 

Figure 9.12 Deoxy derivatives. These contain one less oxygen atom than the monosaccharide from which they are derived. 2-Deoxyribose is a most important deoxy pentose and is a major constituent of deoxyribonucleic acid (DNA). Deoxy hexoses are widely distributed among plants, animals and microorganisms especially as components of complex polysaccharides. Examples are rhamnose (6-deoxymannose), a component of bacterial cell walls, and fucose (6-deoxygalactose), which is often found in glycoproteins and is an important constituent of human blood group substances.

Fortunately from the chemists point of view, there are polysaccharides with blood group activity more readily accessible than those from erythrocytes, and it is with the former that most chemical investigations have been concerned, although the relationship between these and the blood group substances proper from erythrocytes is not yet clear. Indeed the relationship may be no more than a close similarity in chemical structure of some parts of the molecular complex. 

King and Morgan obtained a very active blood group substance from the cystic fluids of individuals of group A and were able to show that it was very similar in properties to the substance they obtained from hog mucin. More recently Morgan and Waddell have reported the isolation of the corresponding O material from group 0 cystic fluid. The sub-... 

The saliva of secretors has been used as a source of blood group substances in several investigations. Landsteiner obtained very active material from horse saliva and was able to show that it contained D-galac-tose and a hexosamine. More recently the same author compared the blood group substances from the saliva of individuals of groups A, B and 0 and found that there was very little difference in their properties (see Table III). 

Although no complete investigations of the structure of the blood group substances have yet been reported, it is evident from the information available that all the material so far studied is predominantly carbohydrate in nature, and, as can be seen from Table III, preparations from widely different sources have many properties in common, for example, elementary analysis, specific rotation and the like. It is of interest to note that almost all the substances obtained from nonhuman sources display blood group A or blood group O activity, while human material is the most convenient source of the blood group B substance. The majority of the work carried out so far has dealt with blood group A substances. 

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