Biomedical subjects

W Reutter

Publications and source records attributed to W Reutter.

At least 55 records · Page 3Linked to original sources

PubMed1998

Collagen type I modulates the platelet-derived growth factor (PDGF) regulation of the growth and expression of beta1 integrins by rat mesangial cells.

Mesangial cell (MC) proliferation and the deposition of collagen type I (collagen I) are the major pathological features in many types of glomerulonephritis (GN). Recent work suggested that beta-integrins play a critical role in the cell proliferation and extracellular matrix (ECM) remodeling observed in tissue repair after injury. To examine the involvement of beta-integrins in MC proliferation in association with the interaction of MCs with pathological collagen I, we investigated the effect of a prominent mitogen, platelet-derived growth factor-BB (PDGF-BB) on the growth and expression of beta-integrins by MCs cultured on plastic or in a three-dimensional collagen I gel. Immunoprecipitation using 35S-metabolic labeling, flow cytometry and a 3H-thymidine-uptake analysis demonstrated that PDGF-BB stimulated the cell mitogenicity and the expression of alpha5beta1 integrin (a fibronectin receptor), but not alpha1beta1 integrin (a collagen and laminin receptor) of MCs on plastic, in a dose-dependent manner. In contrast, MCs in the collagen I gels showed no significant changes in mitogenicity or alpha1beta1 and alpha5beta1 integrin expression, but increased alpha1beta1 integrin-mediated gel contraction was observed after PDGF-BB stimulation. Thus, the parallel up-regulation of MC-mitogenicity and alpha5beta1 integrin expression by PDGF-BB suggested that alpha5beta1 integrin is an important ECM receptor involved in the proliferative phenotype of MC. A spatial interaction between MCs and pathological collagen I in GN may influence the PDGF regulation of the MC phenotype regarding the cell growth and the expression of beta1 integrins.

Animals↗

PubMed1998

Carcinoembryonic antigen-related cell-cell adhesion molecule C-CAM is greatly increased in serum and urine of rats with liver diseases.

C-CAM (rat cell CAM/human CD66a) is ubiquitous and multifunctional. It is involved in intercellular adhesion, signal transduction and cell growth inhibition. Structurally, it is related to the carcinoembryonic antigen. In the present study serum, bile and urine of rats with liver diseases were analyzed for the presence of cell CAM. After bile duct ligation and during galactosamine (GalN) hepatitis we found that large amounts of liver membrane-bound C-CAM are secreted or shed into blood. The serum level of another liver membrane-bound protein, LI-cadherin, is not increased. It was shown that C-CAM is also present in bile fluid, and for the first time that C-CAM is present in the urine of rats with liver diseases. A particularly high concentration was measured in the urine of rats suffering from GalN hepatitis.

Animals↗

PubMed1998

Biochemical engineering of neural cell surfaces by the synthetic N-propanoyl-substituted neuraminic acid precursor.

Sialylation of glycoproteins and glycolipids plays an important role during development, regeneration, and pathogenesis of diseases. During times of intense plasticity within the nervous system, such as development and regeneration, sialylation of neural cells is distinct from the time of its maintenance. In this study, a synthetic precursor of neuraminic acid, N-propanoylmannosamine (N-propanoyl neuraminic acid precursor (P-NAP)), is applied to the culture medium of oligodendrocyte progenitor cells, microglia, astrocytes, and neurons from neonatal rat brains to alter sialylation of glycoconjugates within these cells. P-NAP is metabolized and incorporated as N-propanoyl neuraminic acid into glycoproteins of the cell membrane. P-NAP stimulates the proliferation of astrocytes and microglia but not of oligodendrocyte progenitor in vitro. However, P-NAP increases the number of oligodendrocyte progenitor cells expressing the early oligodendroglial surface marker A2B5 epitope. In the presence of P-NAP, cerebellar neurons (but not astrocytes) in microexplant cultures start to express the oligodendroglial progenitor marker A2B5 epitope, which is normally undetectable on these cells. The controls, which were performed in the absence of any additive or in the presence of the physiological precursor of neuraminic acid, N-acetylmannosamine, did not show any increase in A2B5 expression.

Animals↗

PubMed1998

Rat dipeptidyl peptidase IV (DPP IV) exhibits endopeptidase activity with specificity for denatured fibrillar collagens.

Dipeptidyl peptidase IV (DPP IV, CD 26) is an integral membrane serine protease exhibiting a well characterized exopeptidase activity. The present study shows that DPP IV also possesses a novel gelatinase activity and therefore endopeptidase activity, which was directly demonstrated by gelatin zymography. Protease inhibitor profile analysis showed that the endo- and exopeptidase activities of DPP IV share a common active site. Substrate specificity was detected for denatured collagen types I, II, III and V suggesting that DPP IV might contribute to collagen trimming and metabolism. On the basis of these data we propose that DPP IV and the recently sequenced gelatinolytic seprase (FAPalpha) represent a new subfamily of gelatinolytic integral membrane serine proteases.

Animals↗

PubMed1998

Focal adhesion kinase pp125FAK and the beta 1 integrin subunit are constitutively complexed in HaCaT cells.

Binding of integrins to the extracellular matrix (ECM) activates various signal transduction pathways and regulates gene expression in many cell types. Integrin-dependent cytoplasmic protein/protein interactions are necessary for activation of those signal transduction cascades. In our studies we investigated a possible association of pp125FAK, an adhesion involved tyrosine kinase, with the integrin beta 1 subunit. Further we wanted to know to which extent protein tyrosine phosphorylation affects cell adhesion to the ECM and the possible beta 1 integrin/pp125FAK complex. We were able to show that in HaCaT cells (a human keratinocyte derived cell line) the integrin beta 1 subunit is associated with tyrosine kinase pp125FAK. This association was observed in ECM-adherent cells and nonadherent cells and is independent of tyrosine phosphorylation. However, cell adhesion of HaCaT cells to specific substrates requires tyrosine phosphorylation since genistein treatment that blocks phosphorylation of many cellular proteins as pp125FAK led to a reduced substrate adhesion.

Carcinoma, Squamous Cell↗

PubMed1998

Purification and characterization of N-acetylglucosamine kinase from rat liver--comparison with UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase.

N-Acetylglucosamine, a major sugar in complex carbohydrates, enters the pathways of aminosugar metabolism by the action of N-acetylglucosamine kinase (EC 2.7.1.59). In this study we report the purification to homogeneity of GlcNAc kinase from rat liver cytosol using salmine sulfate precipitation, chromatography on phenyl-Sepharose, ATP-agarose and MonoQ, and finally gel filtration on Superdex 200. It was characterized as a dimer of 39-kDa subunits. About 25% of the amino acid sequence of GlcNAc kinase was established by peptide mapping. Part of the ATP-binding site of GlcNAc kinase was identified by sequence comparison with related hexokinases, including the bifunctional enzyme UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase (EC 5.1.3.14/2.7.1.60), the key enzyme of N-acetylneuraminic acid biosynthesis in rat liver. The Cys residues in the active sites of GlcNAc kinase and ManNAc kinase were characterized by chemical modification with N-ethylmaleimide, iodoacetamide and 5,5'-dithiobis(2-nitrobenzoic acid). The finding that the substrates GlcNAc and ManNAc protected their respective enzymes from inhibition by the above sulfhydryl reagents indicates that Cys residues are located in or near the active sites of both enzymes. Use of the specific dithiol-modifying chemical reagents, sodium meta-periodate, sodium meta-arsenite/2,3-dimercaptopropanol and diazenedicarboxylic acid bis-N,N'-dimethylamide revealed that the active sites of GlcNAc kinase and ManNAc kinase possess at least one pair of vicinal thiols. Chemical treatment of UDP-GlcNAc 2-epimerase provided no evidence for the presence of cysteine in the active site of this enzyme. From the incorporation of N-[3H]ethylmaleimide into GlcNAc kinase in the absence and presence of ligands we estimated that the active site of GlcNAc kinase contains two Cys residues.

Acetylglucosamine↗

PubMed1998

Cell surface glycoproteins undergo postbiosynthetic modification of their N-glycans by stepwise demannosylation.

Primary rat hepatocytes and two hepatoma cell lines have been used to study whether high mannose-type N-glycans of plasma membrane glycoproteins may be modified by the removal of mannose residues even after transport to the cell surface. To examine glycan remodeling of cell surface glycoproteins, high mannose-type glycoforms were generated by adding the reversible mannosidase I inhibitor deoxymannojirimycin during metabolic labeling with [3H]mannose, thereby preventing further processing of high mannose-type N-glycans to complex structures. Upon transport to the cell surface, glycoproteins were additionally labeled with sulfosuccinimidyl-2-(biotinamido)ethyl-1,3-dithiopropionate. This strategy allowed us to follow selectively the fate of cell surface glycoproteins. Postbiosynthetic demannosylation was monitored by determining the conversion of Man8-9GlcNAc2 to smaller structures during reculture of cells in the absence of deoxymannojirimycin. The results show that high mannose-type N-glycans of selected cell surface glycoproteins are trimmed from Man8-9GlcNAc2 to Man5GlcNAc2 with Man7GlcNAc2 and Man6GlcNAc2 formed as intermediates. It could be clearly shown in MH 7777 as well as in HepG2 cells that demannosylation affects plasma membrane glycoproteins after they are routed to the cell surface. As was determined for total cell surface glycoproteins in HepG2 cells, this process occurs with a half-time of 6.7 h. By analyzing the size of high mannose-type glycans of glycoproteins isolated from the cell surface at the end of the reculture period, i.e. after trimming had occurred, we were able to demonstrate that glycoproteins carrying trimmed high mannose glycans become exposed at the cell surface. From these data we conclude that cell surface glycoproteins can be trimmed by mannosidases at sites peripheral to N-acetylglucosaminyltransferase I without further processing of their glycans to the complex form. This glycan remodeling may occur at the cell surface or during endocytosis and recycling back to the cell surface.

Animals↗

PubMed1998

Rapid analysis of O-acetylated neuraminic acids by matrix assisted laser desorption/ionization time-of-flight mass spectrometry.

N-Acetylneuraminic acid (a sialic acid) occurs mainly as a terminal substituent of oligosaccharides of glycoconjugates. Derivatives of neuraminic acid occur widely, substituted in the amino and hydroxy side chains, as well in the C-9 carbon skeleton. These derivatives are responsible for specific functions of sialic acids during cell-cell, cell-substrate, or cell-virus interactions. The study of O-acetylated neuraminic acids is difficult, because only small amounts are extractable from natural sources and they are generally unstable to acids and bases. We report a new method for the rapid analysis of O-acetylated neuraminic acids, using a combination of reversed phase HPLC and MALDI-TOF mass spectrometry. A mixture of neuraminic acids from bovine submaxillary gland mucins was analysed, as well as neuraminic acids variously substituted in the amino and hydroxy side chains with acetyl and glycolyl groups, respectively.

Animals↗

PubMed1998

Metal ion requirement of bifunctional UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase from rat liver.

The metal ion requirement for both enzymatic activities of the bifunctional UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase (E.C. 5.1.3.14/2.7.1.60), the key enzyme of N-acetylneuraminic acid biosynthesis in rat liver, was investigated. UDP-N-acetylglucosamine 2-epimerase was active in imidazole/HCl buffer in the complete absence of any metal ion. 200 mM Na+, K+, Rb+ and Cs+ activated enzyme activity up to five-fold, whereas lower concentrations of these monovalent metal ions showed only a small effect on UDP-N-acetylglucosamine 2-epimerase activity. In sodium phosphate buffer the enzyme activity was increased by 0.5 mM Mg2+, Sr2+, Ba2+ and Mn2+, while in the presence of 200 mM NaCl UDP-N-acetylglucosamine 2-epimerase activity showed a stronger activation by these divalent metal ions. In imidazole/HCl buffer, UDP-N-acetylglucosamine 2-epimerase activity was partially inhibited by 0.5 mM Be2+, Mg2+, Ba2+, Mn2+, Sn2+ and Fe2+, and completely inhibited by 0.5 mM Zn2+ and Cd2+. Divalent metal ions were essential for N-acetylmannosamine kinase activity, the most effective being Mg2+, followed by Mn2+ and Co2+. The optimal concentration of these metal ions was 3 mM. Less effective were Ni2+ and Cd2+, whereas Ca2+, Ba2+, Cu2+, Fe2+ and Zn2+ showed no effect on enzyme activity.

Animals↗

PubMed1998

Epithelial uptake and transport of cell-free human immunodeficiency virus type 1 and gp120-coated microparticles.

Cell-free human immunodeficiency virus type 1 (HIV-1) can be taken up and released by a monolayer of primary human gingival cells and remain infectious for CD4+ cells. Virus-sized latex particles covalently coated with purified native HIV-1 envelope glycoprotein gp120 are also transported through the primary epithelial cells. This process is significantly stimulated by increasing the intracellular cyclic AMP (cAMP) concentration. Inhibition experiments with mannan and alpha-methyl-mannopyranoside indicated that mannosyl groups are involved in the interaction between gp120 and gingival cells. An increase of cellular oligomannosyl receptors by incubation with the mannosidase inhibitor deoxymannojirimycin augmented transcellular transport of the gp120-coated particles. The results suggest that infectious HIV can penetrate gingival epithelia by a cAMP-dependent transport mechanism involving interaction of the lectin-like domain of gp120 and mannosyl residues on glycoproteins on the mucosal surface. Penetration of HIV could be inhibited by soluble glycoconjugates present in oral mucins.

Biological Transport↗

PubMed1997

A bifunctional enzyme catalyzes the first two steps in N-acetylneuraminic acid biosynthesis of rat liver. Purification and characterization of UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase.

Biosynthesis of N-acetylneuraminic acid (Neu5Ac), a prominent component of glycoconjugates, is initiated by the action of UDP-N-acetylglucosamine 2-epimerase (UDP-GlcNAc 2-epimerase, EC 5.1. 3.14) and N-acetylmannosamine kinase (ManNAc kinase, EC 2.7.1.60). We demonstrate for the first time that the two activities are parts of one bifunctional enzyme in rat liver. The enzyme was purified to homogeneity from rat liver cytosol using salmine sulfate precipitation and chromatography on phenyl-Sepharose, ATP-agarose, and Mono Q. The purification resulted in one polypeptide with an apparent molecular mass of 75 kDa. Immunoprecipitation with a polyclonal antibody against the polypeptide reduced both enzyme activities in equal amounts. Gel filtration analysis of purified UDP-GlcNAc 2-epimerase/ManNAc kinase showed that the polypeptide self-associates as a dimer and as a hexamer with apparent molecular masses of 150 and 450 kDa, respectively. The hexamer was fully active for both enzyme activities, whereas the dimer catalyzed only the phosphorylation of N-acetylmannosamine (ManNAc). Incubation of the dimer with UDP-N-acetylglucosamine led to reassembly of the fully active hexamer; maximal quantities of the hexamer were produced after incubation for 3 h. Kinetic analysis of purified hexameric and dimeric enzyme revealed significantly lower Michaelis constants (93 +/- 3 to 121 +/- 15 microM for ManNAc and 1.18 +/- 0. 13 to 1.67 +/- 0.20 mM for ATP) and higher cooperativity (Hill coefficients of 1.42 +/- 0.16 to 1.17 +/- 0.06 for ManNAc and 1.30 +/- 0.09 to 1.05 +/- 0.14 for ATP) for the hexamer for both substrates of ManNAc kinase. The Michaelis constant of UDP-GlcNAc 2-epimerase for its substrate was 11 +/- 2 microM. The Hill coefficient of 0.45 +/- 0.07 represents strongly negative cooperativity in substrate binding. UDP-GlcNAc 2-epimerase was feedback inhibited by CMP-Neu5Ac. Complete inhibition was achieved with 60 microM CMP-Neu5Ac, and highly positive cooperativity (Hill coefficient of 4.1) was found for inhibitor binding.

Animals↗

PubMed1997

A bifunctional enzyme catalyzes the first two steps in N-acetylneuraminic acid biosynthesis of rat liver. Molecular cloning and functional expression of UDP-N-acetyl-glucosamine 2-epimerase/N-acetylmannosamine kinase.

N-Acetylneuraminic acid (Neu5Ac) is the precursor of sialic acids, a group of important molecules in biological recognition systems. Biosynthesis of Neu5Ac is initiated and regulated by its key enzyme, UDP-N-acetylglucosamine 2-epimerase (UDP-GlcNAc 2-epimerase, EC 5.1. 3.14)/N-acetylmannosamine kinase (ManNAc kinase, EC 2.7.1.60) in rat liver (Hinderlich, S., Stäsche, R., Zeitler, R., and Reutter, W. (1997) J. Biol. Chem. 272, 24313-24318). In the present paper we report the isolation and characterization of a cDNA clone encoding this bifunctional enzyme. An open reading frame of 2166 base pairs encodes 722 amino acids with a predicted molecular mass of 79 kDa. The deduced amino acid sequence contains exact matches of the sequences of five peptides derived from tryptic cleavage of the enzyme. The recombinant bifunctional enzyme was expressed in COS7 cells, where it displayed both epimerase and kinase activity. Distribution of UDP-GlcNAc 2-epimerase/ManNAc kinase in the cytosol of several rat tissues was investigated by determining both specific enzyme activities. Secreting organs (liver, salivary glands, and intestinal mucosa) showed high specific activities of UDP-GlcNAc 2-epimerase/ManNAc kinase, whereas significant levels of these activities were absent from other organs (lung, kidney, spleen, brain, heart, skeletal muscle, and testis). Northern blot analysis revealed no UDP-GlcNAc 2-epimerase/ManNAc kinase mRNA in the non-secreting tissues.

Amino Acid Sequence↗

PubMed1997

Turnover studies of the neural cell adhesion molecule NCAM: degradation of NCAM in PC12 cells depends on the presence of NGF.

The neural cell adhesion molecule NCAM is a member of the immunoglobulin superfamily and involved in path finding and outgrowth of neurites in vitro. PC12 cells express two major isoforms of NCAM (NCAM180 and NCAM140) and undergo neuronal differentiation, e.g., neurite formation, in response to NGF. Using this cell system, we determined the half-life time of both NCAM isoforms in the absence and presence of NGF. Half-life time of NCAM140 is similar in the presence and absence of NGF, whereas the half-life time of NCAM180 is increased in the presence of NGF. Furthermore, we quantified protein expression of both NCAM isoforms in the presence or absence of NGF and found a decrease of NCAM protein expression in course of neuronal differentiation.

Amino Acid Sequence↗

PubMed1997

Domain-specific N-glycosylation of the membrane glycoprotein dipeptidylpeptidase IV (CD26) influences its subcellular trafficking, biological stability, enzyme activity and protein folding.

Dipeptidyl peptidase IV (DPPIV, CD26) is an N-glycosylated type II plasma membrane protein. The primary structure of rat wild-type DPPIV contains eight potential N-glycosylation sites. To investigate the role of N-glycosylation in the function of DPPIV, three of its asparagine residues were separately converted to glutamine by site-directed mutagenesis. The resulting N-glycosylation mutants of rat DPPIV were studied in stable transfected Chinese hamster ovary cells. All three N-glycosylation mutants of DPPIV showed a reduced half-life, as well as differing degrees of inhibition of the processing of their N-glycans. Mutation of the first (Asn83-->Gln) or eighth (Asn686-->Gln) N-glycosylation site had only a small effect on its enzymatic activity, cell-surface expression and dimer formation, whereas the mutation of the sixth N-glycosylation site (Asn319-->Gln) abolished the enzymatic activity, eliminated cell-surface expression and prevented the dimerization of the DPPIV protein. The mutant [Gln319]DPPIV is retained in the cytoplasm and its degradation was drastically increased. Our data suggest that the N-glycosylation at Asn319 is involved in protein trafficking and correct protein folding.

Animals↗

PubMed1997

Quantification of cell-matrix and cell-cell adhesion using horseradish peroxidase.

A simple, universal, and rapid enzymatic method for the quantitative determination of cell adhesion in 96-well cell culture plates has been established. The assay is based on cellular steady-state endocytosis, which is used to label cells with horseradish peroxidase (HRP) prior to adhesion. Subsequently, attached cells can be detected by a simple enzymatic reaction, in which the accumulated HRP catalyzes dye formation from a colorless hydrogen donor, e.g., o-phenylenediamine, in the presence of hydrogen peroxide. As demonstrated with different cell lines and test systems, the method can be used to quantify cell-matrix as well as cell-cell interactions and allows a very sensitive quantification of adherent cells. The HRP label is nontoxic and does not affect the adhesion properties of tested cell lines; the quantity of dye formed is proportional to the number of adherent cells. Furthermore, the assay represents an alternative method to isotopic cell labeling, e.g., with 51Cr, which is usually used for quantifying cell-cell interactions.

Animals↗

PubMed1997

Analysis of site-specific N-glycosylation of recombinant Desmodus rotundus salivary plasminogen activator rDSPA alpha 1 expressed in Chinese hamster ovary cells.

The recombinant plasminogen activator (rDSPA alpha 1) from the vampire bat Desmodus rotundus is a promising new thrombolytic agent that exhibits a superior pharmacological profile if compared to tissue-type plasminogen activator (t-PA) or streptokinase. In the present study the structures of the carbohydrate moieties at the two N-glycosylation sites (Asn-117, Asn-362) of rDSPA alpha 1 expressed in Chinese hamster ovary cells were determined. N-Linked glycans were enzymatically released from isolated tryptic glycopeptides by peptide-N4-(N-acetyl-beta-glucosaminyl)asparagine amidase F digestion and separated by two-dimensional HPLC. Oligosaccharide structures were characterized by analysis of carbohydrate composition and linkage, by mass spectrometry, and by sequence analysis in which the fluorescently labeled glycans were cleaved with an array of specific exoglycosidases. More than 30 different oligosaccharides were identified. The results revealed that Asn-117 carried a mixture of one high-mannose structure (17% of site-specific glycosylation), three hybrid glycans (26%) and predominantly biantennary complex N-glycans (54%). Glycosylation site Asn-362 was found to comprise complex glycans with biantennary (50%), 2,4- and 2,6-branched triantennary (21%, 11%), and tetraantennary structures (10%), which were fucosylated at the innermost residue of N-acetylglucosamine. Mainly neutral and monosialylated glycans, and smaller quantities of disialylated glycans, were detected at both glycosylation sites. Sialic acid was alpha 2-3 linked to galactose exclusively. As shown in this study the N-glycans attached to Asn-117 of rDSPA alpha 1 are more processed during biosynthesis than the high-mannose structures linked to Asn-117 of t-PA, to which the polypeptide backbone of rDSPA alpha 1 is structurally closely related.

Amino Acid Sequence↗

PubMed1997

Consequences of a subtle sialic acid modification on the murine polyomavirus receptor.

Polyomaviruses are small, nonenveloped DNA tumor viruses with restricted host ranges. Virus binding to cell surface receptors is one determinant of viral tropism. Although murine polyomavirus is among the best characterized viruses, little is known about the sialic acid-containing receptor and its interaction with viral particles. By using nonradioactive virus binding assays as recently described for the B-lymphotropic papovavirus, murine polyomavirus particles were found to bind in a saturable and noncooperative manner to 25,000 receptors per 3T6 mouse fibroblast. The virus-receptor interaction at 4 degrees C was of high affinity (Kd = 1.8 x 10(-11) M), very fast (k1 = 1.7 x 10(7) M(-1) s(-1)), and stable (half-life = 38 min). Elongation of the N-acyl side chain of sialic acid by biosynthetic modulation with synthetic precursor analogs has been shown for other polyomaviruses to influence both sialic acid-dependent binding and infection (O. T. Keppler, P. Stehling, M. Herrmann, H. Kayser, D. Grunow, W. Reutter, and M. Pawlita, J. Biol. Chem. 270:1308-1314, 1995). In 3T6 cells in which about one-third of the sialic acids were modified, infection and binding of polyomavirus particles were significantly reduced. The number of receptors per cell was decreased to 18,000, with the remaining receptors displaying the same affinity as in untreated cells. Molecular modeling studies based on the three-dimensional structure of a mouse polyomavirus-sialyllactose complex recently solved by T. Stehle and coworkers (T. Stehle, Y. W. Yan, T. L. Benjamin, and S. C. Harrison, Nature 369:160-163, 1994) were performed. They suggest that the elongation of the N-acyl side chain by a single methylene group leads to steric hinderence, with the peptide backbone of a loop walling the tip of the shallow sialic acid binding groove. This collision appears to be incompatible with functional binding. The data are taken as a basis to discuss possible features of the organization and topology of the cellular receptor for mouse polyomavirus.

Animals↗

PubMed1997

Inhibition of L-fucokinase from rat liver by L-fucose analogues in vitro.

By investigating the effects of more than 15 different L-fucose analogues on the activity of L-fucokinase (EC 2.7.1.52) from rat liver in vitro, certain structural requirements for potent inhibition of this enzyme were established. Of the novel compounds, 4,6-dideoxy-L-xylo-hexopyranose (4) and methyl 4,6-dideoxy-4-iodo-L-glucopyranose (9) were found to be competitive inhibitors with Ki-values of 0.5 mM and 5.0 mM respectively. Thus 4,6-dideoxy-L-xylo-hexopyranose is a better inhibitor of L-fucokinase than methyl-alpha-L-fucoside (1). Uptake of L-fucose into rat hepatoma cells is reduced by 52% in the presence of the deoxy derivative (4), leading to a decrease of 45% in the incorporation of L-fucose into total cellular glycoproteins.

Animals↗