Separation and analysis of glycoprotein oligosaccharides

"Stuck on sugars - how carbohydrates regulate cell adhesion, recognition, and signaling"

We have explored the fundamental biological processes by which complex carbohydrates expressed on cellular glycoproteins and glycolipids and in secretions of cells promote cell adhesion and signaling. We have also explored processes by which animal pathogens, such as viruses, bacteria, and parasites adhere to glycans of animal cells and initiate disease. Glycans important in cell signaling and adhesion, such as key O-glycans, are essential for proper animal development and cellular differentiation, but they are also involved in many pathogenic processes, including inflammation, tumorigenesis and metastasis, and microbial and parasitic pathogenesis. The overall hypothesis guiding these studies is that glycoconjugates are recognized and bound by a growing class of proteins called glycan-binding proteins (GBPs or lectins) expressed by all types of cells. There is an incredible variety and diversity of GBPs in animal cells involved in binding N- and O-glycans, glycosphingolipids, and proteoglycan/glycosaminoglycans. We have specifically studied such molecular determinants recognized by selectins, galectins, and many other C-type lectins, involved in leukocyte recruitment to sites of inflammation in human tissues, lymphocyte trafficking, adhesion of human viruses to human cells, structure and immunogenicity of glycoproteins on the surfaces of human parasites. We have also explored the molecular basis of glycoconjugate biosynthesis by exploring the enzymes and molecular chaperones required for correct protein glycosylation. From these studies opportunities for translational biology have arisen, involving production of function-blocking antibodies, anti-glycan specific antibodies, and synthetic glycoconjugates, e.g. glycosulfopeptides, that specifically are recognized by GBPs. This invited short review is based in part on my presentation for the IGO Award 2019 given by the International Glycoconjugate Organization in Milan.

Optimization of the enzymatic one pot reaction for the synthesis of uridine 5'-diphosphogalactose

Five recombinant Escherichia coli extracts harboring overexpressed galactokinase, galactose-1-phosphate uridyltransferase, UDP-glucose pyrophophorylase, UMP kinase, and acetate kinase (AK) were utilized for the production of UDP-galactose (UDP-Gal). We analyzed the parameters which limit the yield of UDP-Gal in the reaction, and the reaction was optimized by increasing the concentration of AK. AK was used for the ATP regeneration as well as the conversion of UDP to UTP. The activities of four overexpressed enzymes were identically fixed, and then we increased the activity of AK to 20 times higher than others. The extracts catalyzed the production of UDP-Gal from UMP (10 mM), galactose (12 mM), ATP (1 mM), and acetyl phosphate (40 mM). As the result of the reaction, the conversion yield of UDP-Gal reached to 95% from 10 mMUMP.

Metabolic radiolabeling of animal cell glycoconjugates

Useful information about glycoconjugates can be obtained by labeling their aglycone (noncarbohydrate) portions-e.g., labeling proteins with radioactive amino acids-and then using techniques described elsewhere in this chapter to infer the presence, type, and nature of glycan chains. This unit describes metabolic labeling techniques that provide more specific information about the structure, sequence, and distribution of the sugar chains of glycoconjugates. Following metabolic labeling, the radioactive glycoconjugate of interest is isolated, individual glycosylation sites are identified and separated if necessary, and the labeled glycans are subjected to structural analysis.

Metabolic radiolabeling of animal cell glycoconjugates

Useful information about glycoconjugates can be obtained by labeling their aglycone (noncarbohydrate) portions--e.g., labeling proteins with radioactive amino acids--and then using techniques described elsewhere in this chapter to infer the presence, type, and nature of glycan chains. This unit describes metabolic labeling techniques that provide more specific information about the structure, sequence, and distribution of the sugar chains of glycoconjugates. Following metabolic labeling, the radioactive glycoconjugate of interest is isolated, individual glycosylation sites are identified and separated if necessary, and the labeled glycans are subjected to structural analysis.

Metabolic radiolabeling of animal cell glycoconjugates

This unit describes metabolic labeling techniques that provide specific information about the structure, sequence, and distribution of the sugar chains of glycoconjugates. In the Basic Protocol, cells in culture are grown through several population doublings in complete medium supplemented with radiolabeled glycoconjugate precursors to reach a steady-state level of incorporation. In the alternate protocols, cells are cultured for a short period of time in a deficient medium that contains a high concentration of radiolabeled precursor. A pulse or pulse-chase labeling procedure is provided to analyze precursor-product relationships. With the sequential pulse-labeling method described here, it is possible to obtain quantities of labeled glycoconjugates with the use of a minimum amount of labeled precursor by using the same batch of medium to pulse-label a series of cultures. A support protocol describes the preparation of multiply deficient medium (MDM) for use in making appropriate deficient media.

Overview of glycoconjugate analysis

Whereas DNA, RNA, and proteins are linear polymers that can usually be directly sequenced, oligosaccharides show substantially more complexity,having branching and anomeric configurations (alpha and beta linkages). The biosynthesis of oligosaccharides, termed glycosylation, is extremely complex, is not template-driven, varies among different cell types, and cannot be easily predicted from simple rules. This overview discusses the stereochemistry of mono- and oligosaccharides and provides diagrammatic representations of monosaccharides (Fisher projections and Haworth representations) and formulas for representation of oligosaccharide chains. A glossary of terms used in glycobiology is also provided.

Metabolic radiolabeling of animal cell glycoconjugates

This unit describes metabolic labeling techniques that provide specific information about the structure, sequence, and distribution of the sugar chains of glycoconjugates. Although these techniques provide less information than complete sequencing of the sugar chains, the partial structural information derived is sufficient for many purposes. In the basic procedure presented in this unit, actively growing cell cultures are grown through several population doublings in complete medium supplemented with radiolabeled glycoconjugate precursors to reach a steady-state level of incorporation. In alternate protocols, cells are cultured for a short period of time in a deficient medium that contains a high concentration of radiolabeled precursor. A pulse or pulse-chase labeling procedure can be used to analyze precursor-product relationships. With sequential pulse-labeling, it is possible to obtain quantities of labeled glycoconjugates with the use of a minimal amount of labeled precursor by using the same medium to pulse-label a series of cultures. A support protocol describes the preparation of multiply deficient medium (MDM) for use in making appropriate deficient media.

Core fucosylation of N-linked glycans in leukocyte adhesion deficiency/congenital disorder of glycosylation IIc fibroblasts

Leukocyte adhesion deficiency/congenital disorder of glycosylation IIc (LAD II/CDG IIc) is a genetic disease characterized by a decreased expression of fucose in glycoconjugates, resulting in leukocyte adhesion deficiency and severe morphological and neurological abnormalities. The biochemical defect is a reduced transport of guanosine diphosphate-L-fucose (GDP-L-fucose) from cytosol into the Golgi compartment, which reduces its availability as substrate for fucosyltransferases. The aim of this study was to determine the effects of a limited supply of GDP-L-fucose inside the Golgi on core fucosylation (alpha1,6-fucose linked to core N-acetylglucosamine [GlcNAc]) of N-linked glycans in LAD II fibroblasts. The results showed that, although [3H]fucose incorporation was generally reduced in LAD II cells, core fucosylation was affected to a greater extent compared with other types of fucosylation of N-linked oligosaccharides. In particular, core fucosylation was found to be nearly absent in biantennary negatively charged oligosaccharides, whereas other types of structures, in particular triantennary neutral species, were less affected by the reduction. Expression and activity of alpha1,6-fucosyltransferase (FUT8) in control and LAD II fibroblasts were comparable, thus excluding the possibility of a decreased activity of the transferase. The data obtained confirm that the concentration of GDP-L-fucose inside the Golgi can differentially affect the various types of fucosylation in vivo and also indicate that core fucosylation is not dependent only on the availability of GDP-L-fucose, but it is significantly influenced by the type of oligosaccharide structure. The relevant reduction in core fucosylation observed in some species of oligosaccharides could also provide clues for the identification of glycans involved in the severe developmental abnormalities observed in LAD II.

Characterization of the O-linked oligosaccharide structures on P-selectin glycoprotein ligand-1 (PSGL-1)

P-selectin glycoprotein ligand-1, PSGL-1, a specific ligand for P-, E-, and L-selectin, was isolated from in vivo [3H]-glucosamine labeled HL-60 cells by a combination of wheat germ agglutinin and platelet P-selectin- or E-selectin receptor globulin-agarose chromatography. The O-linked oligosaccharides on the ligand were released by mild alkaline sodium borohydride treatment and analyzed by a combination of ion-exchange, size exclusion, lectin, and paper chromatography, together with specific exoglycosidase treatments and chemical modifications. Approximately 91% of the radioactivity released from PSGL-1 was recovered in five O-linked glycans: GalNAc (approximately 4% of the total structures), Galp, 3GalNAc (36%), and Galbeta, 3GalNAc substituted with one (45%), two (6%), or three (3%) N-acetyllactosamine repeat units. None of these structures contained fucose, and the majority were substituted with at least one sialic acid. The N-acetyllactosmine-containing structures appeared to be core 2. The remaining 9% of the radioactivity recovered in O-linked oligosaccharides from PSGL-1, eluted in two peaks at 11.8 and 10.2 glucose units, on size-exclusion chromatography. Results from lectin chromatography and chemical and enzymatic degradation experiments suggest that the major portion of the radioactivity in these peaks is associated with sialylated N-acetyllactosamine-type oligosaccharides, substituted with fucose at the penultimate residue in the nonreducing end. Since both sialic acid and fucose reportedly are crucial requirements for selectin binding, these results suggest that only a minor portion, approximately 4.5%, of the O-linked oligosaccharides on PSGL-1 are involved in the interaction with the selectins.

Expression of mucin-associated tumor antigens is altered by cell density

Mucin-associated sialylated Lewis antigens are implicated in tumor cell metastasis and are used in several tests for pancreatic cancer. Despite their clinical importance, little is known about the structures of the oligosaccharides of pancreatic cancer mucins or about the regulation of their synthesis or of the synthesis of their protein cores. In this study, we examined the effects of culture at high cell density on the expression of these antigens in the SW1990 human pancreatic cancer cell line. Mucins from cells that were 2.5 weeks post-confluent had increased expression of sialyl-Lewis(a) and Lewis(x) antigens but reduced expression of the DU-PAN-2 antigen (NeuAc alpha2,3Galbeta1,3GlcNAc-Gal-R) when compared to mucins from 1 day post-confluent cells. Sialyl-Lewis antigens differ from the DU-PAN-2 antigen by the presence of an additional fucose. Mucins from 2.5-week cells also had increased binding to lectins specific for fucose, such as AAL and UEAI, with no apparent change in the binding of lectins specific for sialic acids. Metabolically radiolabeled O-linked oligosaccharides with sialyl-Lewis(a) antigenic reactivity eluted from Bio-Gel P-10 in the region of sialylated and sulfated oligosaccharides. Oligosaccharides eluted from QAE-Sephadex (2 mM Tris base) in a pattern suggesting the presence of 1, 2 and 3 or more negative charges per oligosaccharide. Even after desialylation and desulfation, oligosaccharides eluted from Bio-Gel P-10 with apparent molecular sizes greater than glucose oligomers of 12 units. Culture of SW 1990 cells at high density also increased the steady-state levels of mRNA for mucins MUC1, 2, 4, 5 and 6. In summary, after prolonged culture at high cell density, SW1990 cells have qualitative changes in their oligosaccharides that may be due to up-regulation of fucosyltransferases.

Purification and analysis of a polydnavirus gene product expressed using a poly-histidine baculovirus vector

The VHv1.1 polydnavirus gene has been implicated in suppressing the encapsulation response in parasitized insects [Li and Webb (1994) J. Virol. 68, 7482-7489]. In order to characterize this gene product and to further our analysis of its immunosuppressive function, we expressed the VHv1.1 using a custom-designed C-terminal poly-histidine baculovirus vector which allows for high expression and single-step purification of the protein. The 34 kDa VHv1.1 protein was expressed in baculovirus-infected cell cultures and in H. virescens larvae. Highly enriched preparations of the secreted VHv1.1 protein were obtained after affinity chromatography using a NTA-(Ni2+) resin. Characterization with purified preparations of the VHv1.1 protein established that the protein is N-glycosylated, containing glycogroups which are PNGase F-sensitive but Endo H-resistant. The recombinant VHv1.1 protein bound to hemocytes in vitro and in vivo and was endocytosed in a manner similar to the native protein produced in CsPDV-infected larvae.

In vitro glycosylation of proteins: an enzymatic approach

The glycosylation pathway is the most important post-translational modification of a protein and is moreover a highly specific process. The majority of proteins of pharmaceutical interest are glycoproteins. Therefore, it is necessary to identify the composition, the structure, the function and the biosynthesis of the glycoproteins. The present knowledge is described here. In addition, the performed studies about structure-function relationship of the glycoproteins have shown that the oligosaccharide part of a glycoprotein confers important and specific biological roles. Thus, the modification of the structure of the glycan chains can lead to a modification of the activity of the glycoprotein. This phenomenon is encountered at the time of the production of recombinant glycoprotein in a heterologous system. Indeed, the glycosylation profile of a protein is specific to both the host cell and the culture conditions of this cell. Thus, the advantages and the drawbacks of the different host cells used for the glycosylation engineering are presented. In this way, the identification of the different specific enzymes glycosyltransferases and glycosidases involved in the glycosylation pathway is now necessary to improve the production of recombinant glycoprotein. The structure and the characteristics of these enzymes, and more particularly the oligosaccharyltransferase and the galactosyltransferase, are also described.

The analysis of fluorophore-labeled carbohydrates by polyacrylamide gel electrophoresis

The glycans of glycoconjugates mediate numerous important biological processes. Their separation and structural determination present considerable difficulties because of the small quantities that are available from biological sources and the inherent difficulty of analyzing the wide variety of complex structures that exist. A method for the analysis of reducing saccharides by PAGE that uses specific fluorophore labeling and is simple, rapid, sensitive, and readily available to biological researchers, has been developed. This method is known acronimically either as PAGEFS (PAGE of Fluorophore-labeled Saccharides) or in one commercial format as FACE (Fluorophore-Assisted Carbohydrate Electrophoresis). In the PAGEFS method, saccharides having an aldehydic reducing end group are labeled quantitatively with a fluorophore and then separated with high resolution by PAGE. Two fluorophores, 8-aminonaphthalene-1,3,6-trisulfonic acid (ANTS) and 2-aminoacridone (AMAC), have been used to enable the separation of a variety of saccharide positional isomers, anomers, and epimers. Subpicomolar quantities of individual saccharides can be detected using a sensitive imaging system. Mixtures of oligosaccharides obtained by enzymatic cleavage from glycoproteins can be labeled and electrophoresed to yield an oligosaccharide profile of each protein. AMAC can be used to distinguish unequivocally between acidic and neutral oligosaccharides. Methods of obtaining saccharide sequence information from purified oligosaccharides have been developed using enzymatic degradation. Other applications and the potential of the system are described.

Fluorophore-assisted carbohydrate electrophoresis technology and applications

Carbohydrates, in particular the complex carbohydrates conjugated to proteins and lipids, have important functions in a variety of biological systems. Their isolation and structural determination--prerequisites for elucidation of their biological functions--have been technical challenges for many decades. Almost all available chromatographic and electrophoretic methods as well as NMR and MS have been applied to carbohydrate analysis but none has proved satisfactory in terms of simplicity, sensitivity, reproducibility, cost and requirement for materials. Recently, a technique called fluorophore-assisted carbohydrate electrophoresis was developed which is very promising. It separates fluorescently-labeled carbohydrates on polyacrylamide gels and uses a charge-coupled device camera to detect and quantitate the products. This review describes the principles of the method and its applications to several aspects of research on carbohydrate-containing biological biomolecules.

Human immunodeficiency virus type 1 envelope glycoprotein is modified by O-linked oligosaccharides

The human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein has been shown to be extensively modified by N-linked glycosylation; however, the presence of O-linked carbohydrates on the glycoprotein has not been firmly established. We have found that enzymatic deglycosylation of the HIV-1 envelope glycoprotein with neuraminidase and O-glycosidase results in a decrease in the apparent molecular weight of the envelope glycoprotein. This result was observed in both vaccinia virus recombinant-derived envelope glycoproteins and glycoproteins derived from the IIIB, SG3, and HXB2, strains of HIV-1. The decrease in molecular weight was also observed when the envelope glycoprotein had been deglycosylated with N-glycanase F after treatment with neuraminidase and O-glycosidase, indicating that the decrease in apparent molecular weight was not attributable to the removal of N-linked carbohydrate. Treatment with neuraminidase, O-glycosidase, and N-glycanase F was found to be necessary to remove all radiolabel from [3H]glucosamine-labelled envelope glycoprotein, a result seen for both recombinant and HIV-1-derived envelope glycoprotein. [3H]glucosamine-labelled carbohydrates liberated by O-glycosidase treatment were separated by paper chromatography and were found to be of a size consistent with O-linked oligosaccharides. We, therefore, conclude that the HIV-1 envelope glycoprotein is modified by the addition of O-linked carbohydrates.

Protein glycosylation. Structural and functional aspects

During the last decade, there have been enormous advances in our knowledge of glycoproteins and the stage has been set for the biotechnological production of many of them for therapeutic use. These advances are reviewed, with special emphasis on the structure and function of the glycoproteins (excluding the proteoglycans). Current methods for structural analysis of glycoproteins are surveyed, as are novel carbohydrate-peptide linking groups, and mono- and oligo-saccharide constituents found in these macromolecules. The possible roles of the carbohydrate units in modulating the physicochemical and biological properties of the parent proteins are discussed, and evidence is presented on their roles as recognition determinants between molecules and cells, or cell and cells. Finally, examples are given of changes that occur in the carbohydrates of soluble and cell-surface glycoproteins during differentiation, growth and malignancy, which further highlight the important role of these substances in health and disease.

Human myelin/oligodendrocyte glycoprotein: a new member of the L2/HNK-1 family

Myelin/oligodendrocyte glycoprotein (MOG) is a quantitatively minor component of CNS myelin. In this study, human MOG was found to express the L2/HNK-1 epitope on N-linked oligosaccharide structures. This carbohydrate epitope has been found previously in three other characterized human myelin glycoproteins: the myelin-associated glycoprotein, P0, and the oligodendrocyte-myelin glycoprotein. It seems, therefore, that the L2/HNK-1 epitope is expressed frequently in human myelin glycoproteins. Serial lectin affinity chromatography of 14C-glycopeptides indicated that MOG N-oligosaccharide structures are mainly of the complex type, accounting for 77.8% of total radioactivity. In contrast with myelin-associated glycoprotein and P0, which express the L2/HNK-1 epitope on fucosylated structures, in MOG the epitope was detected on all glycopeptide fractions obtained by serial lectin affinity chromatography, although a preferential expression of the L2/HNK-1 epitope was observed on fucosylated structures. Finally, the data indicated that, as for other human myelin glycoproteins, only a subpopulation of MOG molecules expresses the L2/HNK-1 epitope.

Complex-type N-linked oligosaccharides of gp120 from human immunodeficiency virus type 1 contain sulfated N-acetylglucosamine

The major envelope glycoproteins gp120 and gp41 of human immunodeficiency virus type 1, the causative agent for human AIDS, contain numerous N-linked oligosaccharides. We report here our discovery that N-acetylglucosamine residues within the complex-type N-linked oligosaccharides of both gp120 and its precursor, gp160, are sulfated. When human Molt-3 cells persistently infected with human T-cell leukemia virus IIIB were metabolically radiolabeled with 35SO4, gp160, gp120, and to some extent gp41 were radiolabeled. The 35SO4-labeled oligosaccharides were quantitatively released by N-glycanase treatment and were bound by immobilized Ricinus communis agglutinin I, a lectin that binds to terminal beta-galactosyl residues. The kinetics of release of sulfate upon acid hydrolysis from 35SO4-labeled gp120 indicate that sulfation occurs in a primary sulfate ester linkage. Methylation analysis of total glycopeptides from Molt-3 cells metabolically radiolabeled with [3H]glucosamine demonstrates that sulfation occurs at the C-6 position of N-acetylglucosamine. Fragmentation of the gp120-derived 35SO4-labeled glycopeptides by treatment with hydrazine and nitrous acid and subsequent reduction generated galactosyl-anhydromannitol-6-35SO4, which is the expected reaction product from GlcNAc-6-sulfate within a sulfated lactosamine moiety. Charge analysis of the [3H]galactose- and [3H]glucosamine-labeled glycopeptides from gp120 and gp160 indicates that approximately 14% of the complex-type N-linked oligosaccharides are sulfated.

Comparison of the N-Linked Oligosaccharide Structures of the Two Major Human Myelin Glycoproteins MAG and P0: Assessment and Relative Occurrence of Oligosaccharide Structures by Serial Lectin Affinity Chromatography of14C-Glycopeptides

The N-linked oligosaccharide structures of human myelin-associated glycoprotein (MAG) and P0 have been characterized by serial lectin affinity chromatography (SLAC) of 14C-glycopeptides. 14C-Glycopeptides were prepared from purified MAG derivative and P0 by extensive proteolytic digestion and N-14C-acetylation. Assuming that all the 14C-glycopeptides were radiolabelled to the same specific radioactivity, the relative occurrence of the oligosaccharide structures was correlated to the amount of incorporated radioactivity. Sixteen and 15 fractions were generated by SLAC of MAG and P0 14C-glycopeptides, respectively. Despite this tremendous structural heterogeneity, the oligosaccharide "fingerprints" of MAG and P0 obtained by SLAC displayed similarities: (a) of the three types of N-linked oligosaccharides, the complex type accounted for 80.4% and 94.9% of MAG and P0 radioactivity, respectively; (b) biantennary complex oligosaccharides were the major structures present on MAG and P0; (c) approximately 60% of MAG and P0 oligosaccharides possessed a bisecting N-acetylglucosamine residue; and (d) large amounts of oligosaccharides with an alpha(1-6)fucose residue were found in both MAG and P0 and, noticeably, approximately 25% of the tri- and/or tetraantennary and approximately 90% of the bisected biantennary oligosaccharides of both glycoproteins contained alpha(1-6)fucose residues in the core. This study demonstrates that MAG and P0, both belonging to the immunoglobulin superfamily, display structural similarities in their N-linked oligosaccharide contents.

Complex carbohydrates in drug development

Recent advances in carbohydrate chemistry and biochemistry afford the opportunity to develop bioactive complex carbohydrates, per se , as drugs or as lead compounds in drug development. Complex carbohydrates are unique among biopolymers in their inherent potential to generate diverse molecular structures. While proteins vary only in the linear sequence of their monomer constituents, individual monosaccharides can combine at any of several sites on each carbohydrate ring, in linear or branched arrays, and with varied stereochemistry at each linkage bond. This chapter addresses some salient features of mammalian glycoconjugate structure and biosynthesis, and presents examples of the biological activities of complex carbohydrates. The chapter presents selected examples that will provide an accurate introduction to their pharmacological potential. In addition to their independent functions, oligosaccharides can modify the activities of proteins to which they are covalently attached. Many glycoprotein enzymes and hormones require glycosylation for expression and function. The chapter discusses the ancillary role of carbohydrates that is of great importance to the use of engineered glycoproteins as pharmaceuticals.

Identification of a carbohydrate-based endothelial ligand for a lymphocyte homing receptor

Lymphocyte attachment to high endothelial venules within lymph nodes is mediated by the peripheral lymph node homing receptor (pnHR), originally defined on mouse lymphocytes by the MEL-14 mAb. The pnHR is a calcium-dependent lectin-like receptor, a member of the LEC-CAM family of adhesion proteins. Here, using a soluble recombinant form of the homing receptor, we have identified an endothelial ligand for the pnHR as an approximately 50-kD sulfated, fucosylated, and sialylated glycoprotein, which we designate Sgp50 (sulfated glycoprotein of 50 kD). Recombinant receptor binding to this lymph node-specific glycoprotein requires calcium and is inhibitable by specific carbohydrates and by MEL-14 mAb. Sialylation of the component is required for binding. Additionally, the glycoprotein is precipitated by MECA-79, an adhesion-blocking mAb reactive with lymph node HEV. A related glycoprotein of approximately 90 kD (designated as Sgp90) is also identified.

Schistosoma mansoni contains a galactosyltransferase activity distinct from that typically found in mammalian cells

It has been reported previously that some complex-type Asn-linked oligosaccharides contained in glycoproteins synthesized by Schistosoma mansoni adult males contain terminal galactosyl residues. We report here that extracts from S. mansoni adult male and female worms contain a beta 1,4-galactosyltransferase activity that transfers galactose from the donor substrate UDP-galactose to the acceptor substrate N-acetylglucosamine in a beta 1,4-linkage position to form the disaccharide Gal beta 1,4GlcNAc. In this respect the schistosome-derived activity is similar to that commonly found in mammalian tissues. The kinetic properties, however, of the common beta 1,4-galactosyltransferase activity in mammalian tissues are dramatically altered in the presence of the modifier protein alpha-lactalbumin, whereas the beta 1,4-galactosyltransferase activities in adult male and female schistosomes are not altered by this modifier. Overall, our results demonstrate that adult schistosomes contain a beta 1,4-galactosyltransferase activity and that it is unlike that commonly found in mammalian tissues.