Helmut Schenkel-Brunner

Occurrence and assay of alpha-N-acetylgalactosaminyl transferase in the gastric mucosa of humans belonging to blood group A.

According to a current and well-documented hypothesis, the last step in the biosynthesis of blood-group A substance consists in the attachment of a terminal GalNAc residue to a precursor molecule El]. In the case of water-soluble blood-group A substance, the precursor is blood-group H substance. The enzyme catalyzing the last step of the synthesis of A substance is under the control of the blood-group A gene [2]. The blood-group A character of an individual or a human tissue is usually defined by ascertaining serologically or immunochemically the presence of blood-group A substance in the specimen tested. It would be of great interest, however, t o be able t o determine, in addition, the presence or absence in a tissue of the A-synthesizing enzyme. This enzyme is a more direct product of the blood-group A gene than the blood-group A substance, the formation of which is dependent not only on this enzyme, but also on the availability of group H substance. Recently an enzyme was found in hog gastric mucosa which catalyzes the transfer of radioactive GalNAc from labelled UDP-GalNAc t o blood-group substance [3]. When a partially purified soluble preparation of this enzyme was incubated with porcine blood-group H substance and tritium-labelled UDP-GalNAc in the presence of Mn++, blood-group A activity appeared, which could be assayed by hemagglutination inhibition tests [4]. In this communication the occurrence of a similar N-acetylgalactos-

A simple and efficient method for the preparation of GDP-fucose.

Abstract A crude extract from hog submaxillary gland was found to synthesize guanosine diphosphate (GDP)-fucose, when incubated with fucose, ATP and GTP, the two enzymatic steps (fucose fucose-1-phosphate GDP-fucose) proceeding without noticeable side reactions. Column chromatography on Dowex 1 (HCO 3 − ), gel filtration on Sephadex G-15 and preparative paper chromatography gave pure GDP-fucose in an overall yield of 81%. The sugar nucleotide was shown to be active as a glycosyl donor in fucose-incorporating systems.

Evidence for erythrocyte membrane glycoproteins being carriers of blood-group P1 determinants.

The contribution of different membrane constituents to the bloodgroup P1 activity of human erythrocytes was investigated. Pronase digestion of native red cell stroma or partition between butanol and water had no serologically detectable effect, whereas pronase‐treatment of previously butanol‐extracted membranes liberated virtually all blood‐group P1 determinants from the ghosts. On Laemmli gels, all P1 activity was found in the band 4.5 region. Thus it is concluded that, in addition to the well‐documented P1 glycolipid, also membrane glycoproteins are carriers of blood‐group P1 determinants.

Probable Biosynthetic Pathway for the Synthesis of the B Antigen from Bh Variants

Abstract. Red cells and serum from two Bh variants (B+H‐cells) have been investigated for B and H blood group glycosyltransferases. The H enzyme could not be detected using either type 1 or type 2 chain acceptors. The B enzyme was present in normal amount when 2′‐fucosyl‐lactose was used as substrate, neither 6′‐fucosyllactose nor 6′‐fucosyllactosamine could act as acceptors for the B enzyme.

Blood Group ABH Antigens on Human Cord Red Cells

Abstract. When the blood group H sites of cord erythrocytes obtained from newborn infants of groups O, A, B and AB were labelled specifically by incubation of the whole cells with the A1 gene dependent a‐N‐acetylgalactosaminyl transferase in the presence of UDP‐N‐acetyl [14C]‐galactosamine, the incorporation of radioactivity was considerably lower than that found for cells from adults. Based on the amount of label recovered in the membranes, average values of 326,000 H sites per single O cell and 68,000 H sites per single A, B and AB cell were calculated. Following fractionation of the stromal blood group substances thus labelled, it was found that, on the average, 66% of the radioactivity was bound to glycoprotein material, 2.7% to glycosphingolipids with short carbohydrate chains, and about 24% to polyglycosylceramides. As these values are similar to those previously determined for O cells from adults, this result shows that there are probably no substantial differences between erythrocytes from adults and newborn infants concerning the overall membrane disposition, but rather provides evidence for variations in the carbohydrate chains of the stromal glyco‐conjugates.

An improved method for the determination of glycosyltransferases usingpara-nitrophenyl-glycosides as substrates

Due to their easy purification nitrophenyl-glycosides have become of increasing interest as acceptor substrates for the assay of glycosyltransferase activity. In this communication reversed-phase chromatography is shown to provide a convenient means for the isolation of the radioactively labelled nitrophenylglycoside(s) formed in this reaction, superior to the methods hitherto used with regard to speed and specifity.ZusammenfassungNitrophenylglykoside werden immer häufiger als Akzeptor-Substrate bei der Bestimmung von Glykosyltransferase-Aktivitäten verwendet, da sie leicht aus dem Reaktionsgemisch zu isolieren sind. In der vorliegenden Mitteilung wird gezeigt, daß die „reversed-phase“-Chromatographie eine bequeme Möglichkeit darstellt, die bei der Reaktion entstehenden radioaktiv markierten Nitrophenylglykoside zu reinigen. Sie ist den bisher verwendeten Trennmethoden an Geschwindigkeit und Spezifität überlegen.

ABO(H) System

The ABO system was discovered in 1900 by Karl Landsteiner. Based on his assumption of two erythrocyte antigens, A and B, Landsteiner found it possible to classify human individuals into four blood groups depending whether one, both, or neither of these antigenic characters were present on the cells [272,273]. He also recognised that the sera of individuals lacking one or both antigens usually contain anti-A and/or anti-B isoagglutinins (see Table 5.1).

Lewis System and the Antigens X and Y

The detection of the Le a character is generally attributed to Mourant [191], although Ueyama and Furuhata had described it as the ’T-antigen’ in 1939 (see Race and Sanger [212]). Since then the Le b [5,6], Le c [88], Le d [208], and Le x [7] characters of the blood group Lewis system have also been defined(1).

Chido and Rodgers

The character groups Chido (Ch) [18] and Rodgers (Rg) [21] are confined to humans. The antigens are found on erythrocytes [18,21] and in plasma [21,24,26,27], but are absent from tissue cells or secretions [10].

Struktur und Biochemie der Blutgruppenantigene

Anhand eines Aufbaus der determinanten Gruppen der wichtigsten Antigene des Blutgruppen-ABO(H)- und -Lewis-Systems sowie der Biosynthese dieser Strukturen wird gezeigt, inwieweit Untersuchungen uber d