W. T. J. Morgan

Possible genetical pathways for the biosynthesis of blood group mucopolysaccharides.

Certain aspects of the biochemistry and genetics of the human A, B, H and Lea blood group characters are reviewed and, on the basis of the biochemical and genetical data, possible pathways are outlined for the biosynthesis of the water‐soluble mucopolysaccharides which possess blood group specificity.

Further Observations on the Inhibition of Blood‐Group Specific Serological Reactions by Simple Sugars of Known Structure

The chemical nature of the serological determinant units in the water‐soluble B, H, Lea and Leb blood‐group substances have been further studied by the methods of haemagglutination and precipitation inhibition with simple substances of known structure.

The Croonian Lecture A contribution to human biochemical genetics ; the chemical basis of blood-group specificity

In 1900 Landsteiner published the first of his fundamental discoveries which resulted in the division of human bloods into distinct groups and laid the foundation of our present-day knowledge of the specificity of human blood. He showed in a series of simple experiments that when serum and erythrocytes obtained from different persons were mixed together agglutination of the erythrocytes frequently took place, but that in some mixtures no agglutination occurred. It was deduced from these results, and other observations which were obtained somewhat later, that, according to whether or not the red cells contained one or two factors (later designated quite arbitrarily as factors A and B) or neither factor, human bloods could be classified into four groups. The serologically specific agent in the serum, the anti-A or anti-B agglutinin, occurs naturally and brings about the agglutination of those red cells which contain the A or B factors respectively. Antibodies which agglutinate group O cells specifically are not normally found in man and it is, therefore, not possible to detect group O cells directly. Landsteiner concluded from these studies that a person’s serum cannot contain antibody for antigens present in his own erythrocytes, and a definite relationship between different kinds of human blood was revealed and subsequently developed into what is now known as the ABO blood-group system. The relationships, in modern terminology, are given in table 1.

A blood group Sda-active pentasaccharide isolated from Tamm-Horsfall urinary glycoprotein

Human Tamm-Horsfall urinary glycoprotein from an individual of the blood group Sd(a+) phenotype was tritium-labelled by treatment with galactose oxidase and sodium boro[3H]hydride and was then digested with endo-beta-galactosidase. A series of dialysable, labelled fragments was released from which a pentasaccharide was isolated that strongly inhibited the agglutination of Sd(a+) red cells by human anti-Sda serum and hence contained the Sda determinant structure. Reduction, methylation analysis and sequential exo-glycosidase digestion established the structure of the pentasaccharide as: GalNAc beta(1 leads to 4)[NeuAc(2 leads to 3)]Gal beta(1 leads to 4)GlcNAc beta(1 leads to 3)Gal

The nature of the human blood group P1 determinant

Summary A glycoprotein with blood group P 1 specificity isolated from sheep hydatid cyst fluid was subjected to partial acid hydrolysis. The hydrolysis products were separated by preparative paper chromatography. One oligosaccharide with strong P 1 serological activity was characterised as a trisaccharide composed of galactose and glucosamine in the molar ratio of 2:1. Reduction with sodium borohydride gave galactose and glucosaminitol. Methylation analysis and degradation with specific α - and β - galactosidases showed the structure of the P 1 determinant to be D-galactosyl-α(l→4)-D-galactosyl-β(l→4)-N-acetyl-D-glucosamine.

N-acetyl-D-galactosaminyl-β-(1→4)-D-galactose: A terminal non-reducing structure in human blood group Sda-active Tamm-Horsfall urinary glycoprotein

Abstract Human Sda-active Tamm-Horsfall urinary glycoprotein labelled with galactose oxidase and tritiated sodium borohydride was found to contain both galactose and N-acetylgalactosamine as [3H]-labelled terminal non-reducing sugars. Fragmentation of the macromolecule achieved by hydrazinolysis and acid hydrolysis was followed by fractionation of the degradation products by gel filtration, ion exchange and paper chromatography. A major product was a disaccharide which contained unlabelled galactose and [3H]-labelled N-acetylgalactosamine. Sugar analysis, sodium borohydride reduction, methylation analysis and enzymic degradation enabled the structure N-acetyl-D-galactosaminyl-β-(1→4)-D-galactose to be assigned to the disaccharide.

The relationship between the N-acetylgalactosamine content and the blood group Sda activity of Tamm and Horsfall urinary glycoprotein

Substances with the human blood group Sda character occur on red cells and are also present in secretions. In urine Sda activity is associated with the Tamm and Horsfall (T-H) glycoprotein. About 4% of Caucasian individuals, whose red cells are Sda negative, have a T-H glycoprotein that is without Sda activity. The two immunologically distinct forms of T-H glycoprotein have almost identical qualitative and quantitative amino acid and carbohydrate compositions. The only exception is the N-acetylgalactosamine content which falls in the range of 1–2% for preparations from Sd(a+) individuals whereas the level is negligible in the Sda inactive preparations. These results strongly indicate that N-acetylgalactosamine makes an important contribution to the Sda determinant structure in the T-H glycoprotein.

Immunochemical observations on the human blood group P system.

Haemagglutination inhibition experiments were carried out with anti‐P1, anti‐Pk and anti‐P sera in an attempt to increase understanding of the chemical, genetical and serological relationships within the P system. The test‐substances comprised a glycoprotein with human blood group P1 and Pk activity isolated from sheep hydatid cyst fluid, fragments isolated from the partial acid hydrolysis products of the P1Pk active glycoprotein, glycolipids, monosaccharides and di‐ and oligosaccharides of known structure. The trisaccharide αGal(1→4)βGal(1→4)GlcNAc isolated from the glycoprotein hydrolysis products, and earlier established as the P1 determinant (Cory et al., 1974), was the only low molecular weight compound that gave strong inhibition with human, rabbit and goat anti‐P1 sera. A disaccharide αGal(1→4)Gal, also isolated from the glycoprotein hydrolysis products, failed to react with anti‐P1 reagents but inhibited human anti‐Pk sera as strongly as the trisaccharide. The glycolipid αGal(1→4)βGal(1→4)Glc‐Cer (ceramide trihexoside) and other oligosaccharides containing αGal(1→4)Gal at the non‐reducing terminal were also strong inhibitors of anti‐Pk sera. Oligosaccharides with terminal α‐galactosyl residues joined in other positional linkages gave definite, although less strong, inhibition. The inhibition results suggest a close structural relationship between the P1 and Pk determinants and indicate that the specificity of anti‐Pk sera is less closely delineated than that of anti‐P1. Human anti‐P sera differed markedly from anti‐P1 and anti‐Pk and were not inhibited by any of the compounds containing α‐galactosyl residues. The glycolipid βGalNAc(1→3)αGal(1→4)βGal(1→4)Glc‐Cer (globoside) strongly inhibited the anti‐P sera.

Oligosaccharides containing A (1–6) glycosidic linkage obtained from human blood-group specific glycoproteins

Abstract A, B, H, Lea and Leb blood-group active glycoproteins from human secretions and tissue fluids yield many di- and oligosaccharides on partial acid hydrolysis, alkaline degradation and hydrazinolysis. The evidence indicates that in the many carbohydrate chains in each specific substance there is a common pattern of alternate galactose and amino sugar units, but the mature of the glycosidic linkages between the different sugars is not always the same. It is firmly established that 1→3 and 1→4 linkages occur (see Watkins, 1966 ), and there is now evidence ( Yosizawa, 1961 . Lloyd and Kabat, 1967 ) for 1–6 linkages. In this communication the isolation from group specific glycoproteins of a disaccharide, a trisaccharide and a tetrasaccharide each containing a (1→6) linkage is described.

Linkage-specific α-D-galactosidases from Trichomonas foetus: Characterisation of the blood-group B-destroying enzyme as A 1,3-α-galactosidase and the blood-group P1-destroying enzyme as A 1,4-α-galactosidase

Earlier investigations on glycosidases in extracts of the protozoan Trichomonas fbetus indicated that there were at least two distinct ol-D-galactosidases [ 11 ; one acted on low-molecular-weight substrates and differed in heat stability and inhibitory properties from a second enzyme that released a-linked galactose from blood-group B-active structures in glycoproteins. Subsequently the T. foetus extract was found to contain an enzyme that destroyed the blood-group PI activity of a glycoprotein isolated from hydatid cyst fluids [2,3 ] and., as PI specificity is dependent on a terminal non-reducing a-galactosyl residue [3,4] , it was inferred that the enzyme concerned was also an a-galactosidase. The isolation of three linkage-specific ol-D-galactosidases from T. foetus extracts is described in this paper. The enzyme that destroys blood-group B specificity is characterised as a 1,3-a+galactosidase, the enzyme that destroys blood-group PI-specificity as a 1,4-cu-galactosidase, and the third enzyme as a 1,6-c+ galactosidase which also hydrolyses alkyl and aryl a-Dgalactosides.