THE INCORPORATION OF LABELLED AMINO SUGARS BY BACILLUS SUBTILIS

1. N-Acetyl[1-(14)C]glucosamine (10mum-5mm) is incorporated by cells of Bacillus subtilis at a constant rate (0.2-2mmumoles/mg. dry wt./hr.). The rate of [1-(14)C]glucosamine (2.5mum-5mm) incorporation is proportional to the concentration; it approaches that of N-acetyl[1-(14)C]glucosamine at 5mm. 2. Label from N-acetyl-[1-(14)C]glucosamine and [1-(14)C]glucosamine is incorporated predominantly into the ;hot-trichloroacetic acid-soluble' and ;residue' fractions of cells. Acid hydrolysis of the hot-trichloroacetic acid-soluble fraction yields mainly [(14)C]glucosamine; hydrolysis of the residue fraction yields [(14)C]glucosamine and [(14)C]muramic acid. The label from N-[1-(14)C]acetylglucosamine and sodium [1-(14)C]acetate enters most cell fractions. Incorporation of N-[1-(14)C]acetylglucosamine is inhibited by the addition of unlabelled acetate. 3. Glucose competes with [1-(14)C]glucosamine for incorporation. N-Propionylglucosamine and N-formylglucosamine compete with N-acetyl[1-(14)C]glucosamine. 4. Cells pregrown on N-acetylglucosamine or glucosamine incorporate up to ten times as much N-acetyl[1-(14)C]glucosamine or [1-(14)C]glucosamine in a given time as cells pregrown on glucose.

The Chlorella hexose/H+ symporter is a useful selectable marker and biochemical reagent when expressed in Volvox

The multicellular obligately photoautotrophic alga Volvox is composed of only two types of cells, somatic and reproductive. Therefore, Volvox provides the simplest model system for the study of multicellularity. Metabolic labeling experiments using radioactive precursors are crucial for the detection of stage- and cell-type-specific proteins, glycoproteins, lipids, and carbohydrates. However, wild-type Volvox lacks import systems for sugars or amino acids. To circumvent this problem, the hexose/H+ symporter (HUP1) gene from the unicellular alga Chlorella was placed under the control of the constitutive Volvox beta-tubulin promoter. The corresponding transgenic Volvox strain synthesized the sugar transporter in a functional state and was able to efficiently incorporate 14C from labeled glucose or glucosamine. Sensitivity toward the toxic glucose/mannose analogue 2-deoxy-glucose increased by orders of magnitude in transformants. Thus we report the successful transformation of Volvox with a gene of heterologous origin. The chimeric gene may be selected for in either a positive or a negative manner, because transformants exhibit both prolonged survival in the dark in the presence of glucose and greatly increased sensitivity to the toxic sugar 2-deoxyglucose. The former trait may make the gene useful as a dominant selectable marker for use in transformation studies, whereas the latter trait may make it useful in development of a gene-targeting system.

Characterization of a sulfotransferase from human airways responsible for the 3-O-sulfation of terminal galactose in N-acetyllactosamine-containing mucin carbohydrate chains

A galactose 3-O-sulfotransferase activity able to transfer a sulfate group from adenosine 3'-phosphate 5'-phosphosulfate to methyl galactosides or terminal N-acetyllactosamine-containing carbohydrate chains from human respiratory mucins was characterized in microsomal fractions prepared from human respiratory mucosa. The reaction products, methyl alpha- or beta-galactose 3-sulfate and three oligosaccharide alditols containing the sequence HSO3-3Gal beta 1-4GlcNAc beta 1-6GalNAc-itol were identified by high performance anion-exchange chromatography. Using methyl beta-galactoside as a substrate, the optimum activity was obtained with 0.1% Triton X-100, 30 mM NaF, 20 mM Mn2+, and 10 mM AMP in a 30 mM 2-(N-morpholino)ethanesulfonic acid buffer at pH 6.1. The apparent Km for methyl beta-galactoside and for adenosine 3'-phosphate 5'-phosphosulfate were observed at 0.69 x 10(-3) M and at 4 x 10(-6) M respectively. This sulfotransferase is different from that responsible for sulfatide synthesis.

Lamp-1 does not acquire the large polylactosaminoglycans characteristic of F9 cells

Although F9 cells labelled with [3H]glucosamine synthesize many glycoproteins that bind to Datura stramonium agglutinin-agarose, only a small proportion of these were immunoprecipitated with monoclonal antibodies to lamp-1 and lamp-2 (lamp = lysosomal membrane protein). Differentiation of F9 cells by retinoic acid increased labelling of all Datura stramonium-bound glycoproteins, including lamp-1 and lamp-2. Although the large polylactosaminoglycans excluded from Bio-Gel P-6 that are characteristic of F9 cells were obtained from total glycoproteins, little of these large polylactosaminoglycans was found on lamp-1 and lamp-2. There was no increase in large polylactosaminoglycans of lamp-1 and lamp-2 after retinoic acid treatment, but an increase in the size of small polylactosaminoglycans (included on Bio-Gel P-6) and tri- and tetra-antennary complex oligosaccharides. Therefore, other factors besides the expression of specific glycosyltransferases determine the extent of elongation of polylactosaminoglycans on lysosomal membrane proteins.

Nucleotide-activated oligosaccharides are intermediates of the cell wall polysaccharide of Methanosarcina barkeri

The cell wall of Methanosarcina barkeri consists of a heteropolysaccharide (methanochondroitin), which resembles the eukaryotic chondroitin. From cell extracts of Methanosarcina barkeri four uridine diphosphate and one undecaprenyl pyrophosphate-activated intermediate(s) of the methanochondroitin were isolated. In contrast to the known biosynthetic pathways of polysaccharides from other prokaryotes and eukaryotes, nucleotide activated oligosaccharide precursors are involved in the case of the methanochondroitin. Usually, oligosaccharides are synthesized at the lipid stage.

Ionizing groups in lipopolysaccharides of Pseudomonas cepacia in relation to antibiotic resistance

Contrary to previous reports, lipopolysaccharides from Pseudomonas cepacia contain a 3-deoxyoct-2-ulosonic acid (probably a single residue). The lipopolysaccharides contain only two phosphate residues, one of which apparently forms a phosphodiester bridge between 4-amino-4-deoxyarabinose and a glucosamine residue in lipid A. The second, unlocated phosphate residue occurs mainly as a monoester in some lipopolysaccharides, and mainly as a diester in others. All lipopolysaccharides lack pyrophosphate residues. The results support the view that the resistance of P. cepacia to cationic antibiotics stems from ineffective binding to the outer membrane, as a consequence of the low number of phosphate and carboxylate groups in the lipopolysaccharide, and the presence of the protonated aminodeoxypentose.

X-ray and conformational investigations of a 4:1 mixture of 6-(N-benzyl-N-tert-butoxycarbonylamino)-2,3,6,7-tetradeoxy-alpha- DL-ery thro- and -beta-DL-threo-hept-2-enopyranos-4-uloses

The crystals of a 4:1 mixture of 6-(N-benzyl-N-tert-butoxycarbonylamino)-2,3,6,7-tetradeoxy-a-DL-er ythro- and -beta-DL-threo-hept-2-enopyranos-4-ulose were monoclinic, space group P2(1)/c, with cell dimensions: a = 9.490(2), b = 21.516(5), c = 10.279(2) A, beta = 115.31(1) degrees, Z = 4. The ulose ring had a half-chair conformation deformed towards the sofa (envelope) form.

Sulfate incorporation into peripheral nerve endoneurial glycolipids after crush and permanent transection injury

The sulfation of peripheral nerve glycolipids was examined at 35 days after both crush injury or permanent transection of the adult rat sciatic nerve by in vitro incorporation of [35S]sulfate into endoneurial slices. These experimental models of neuropathy are characterized by the presence and absence of both axonal regeneration and subsequent myelin assembly. Although the sulfo-glucuronosyl glycosphingolipids (SGGLs) were not detected by alpha-napthol reagent after HPTLC separation of the total acidic lipid extract, fluorographic analysis after sulfate incorporation revealed a 4.7-fold increase in [35S]sulfate in the sulfo-glucuronosyl paragloboside (SGPG) and a 3.5-fold increase in the sulfo-glucuronosyl-lactosaminosyl paragloboside (SGLPG) after the crush injury compared to permanent transection. These [35S]sulfate-labeled lipids were identified by comigration after HPTLC separation by immunostaining with specific IgM monoclonal antibodies from a patient with demyelinating neuropathy and plasma cell dyscrasia. Enhanced incorporation of sulfate in the crushed nerves was also observed in the sulfatides and in several unknown lipids migrating between GM2 and GM3, between GM1, and GM2, slightly above the origin, and at the origin. Since previous studies (Yao and Poduslo: J Neurochem 50:630-638, 1988) have shown [35S]sulfate incorporation, but not [3H]Gal or [3H]Glc, into sulfatides at 35 days after transection, it is possible that the sulfation observed in the present studies does not represent de novo biosynthesis but rather sulfation of an endogenous pool of glycolipids that results from the nerve injury.(ABSTRACT TRUNCATED AT 250 WORDS)

Structural comparison of anticancer drug-DNA complexes: adriamycin and daunomycin

The anticancer drugs adriamycin and daunomycin have each been crystallized with the DNA sequence d(CGATCG) and the three-dimensional structures of the complexes solved at 1.7- and 1.5-A resolution, respectively. These antitumor drugs have significantly different clinical properties, yet they differ chemically by only the additional hydroxyl at C14 of adriamycin. In these complexes the chromophore is intercalated at the CpG steps at either end of the DNA helix with the amino sugar extended into the minor groove. Solution of the structure of daunomycin bound to d(CGATCG) has made it possible to compare it with the previously reported structure of daunomycin bound to d(CGTACG). Although the two daunomycin complexes are similar, there is an interesting sequence dependence of the binding of the amino sugar to the A-T base pair outside the intercalation site. The complex of daunomycin with d(CGATCG) has tighter binding than the complex with d(CGTACG), leading us to infer a sequence preference in the binding of this anthracycline drug. The structures of daunomycin and adriamycin with d(CGATCG) are very similar. However, there are additional solvent interactions with the adriamycin C14 hydroxyl linking it to the DNA. Surprisingly, under the influence of the altered solvation, there is considerable difference in the conformation of spermine in these two complexes. The observed changes in the overall structures of the ternary complexes amplify the small chemical differences between these two antibiotics and provide a possible explanation for the significantly different clinical activities of these important drugs.

Conformational analysis of the sialyl alpha(2----3/6)N-acetyllactosamine structural element occurring in glycoproteins, by two-dimensional NOE 1H-NMR spectroscopy in combination with energy calculations by hard-sphere exo-anomeric and molecular mechanics force-field with hydrogen-bonding potential

The conformation is described of the sialyl alpha(2----3/6)N-acetyllactosamine structural element, frequently occurring in glycoproteins. NOE spectroscopy of NeuAc alpha(2----3)Gal beta(1----4)GlcNAc beta(1----N)Asn and NeuAc alpha(2----6)Gal beta(1----4)GlcNAc beta(1----N)Asn is presented and for each glycosidic linkage, except for the alpha(2----6)-linkage, a number of interglycosidic NOEs are measured. The analysis of these effects is performed using a full relaxation matrix. Analysis of intraresidue NOEs provides a calibration of the calculation method. Hard-sphere exo-anomeric (HSEA) energy calculations indicate a single conformation for the beta(1----4)-linkage in both compounds, both being consistent with the NOE data. HSEA and molecular-mechanics force-field with hydrogen-bonding potential energy calculations both indicate the existence of three preferred conformations for the alpha(2----3)-linkage. The analysis of the NOE spectra are consistent with a distribution over two or three of these conformations; by combination with the energy diagram for this linkage the existence of onyl a single conformation can be excluded. The NOE spectrum of the compound with the alpha(2----6)-linkage indicates a gt orientation for the Gal C-6 hydroxymethyl group. On this basis, the HSEA energy calculations for the alpha(2----6)-linkage indicate an extended low-energy surface with a number of preferred conformations. The absence of NOEs across this linkage is interpreted in terms of a non-rigid, but overall folded conformation of the NeuAc alpha(2----6)Gal beta(1----4)GlcNAc beta structural element. This provides an explanation for the shift effects induced by alpha(2----6) attachment of NeuAc to the N-acetyllactosamine unit.

Survival of recombinant erythropoietin in the circulation: the role of carbohydrates

Recombinant human erythropoietin produced in transfected Chinese hamster ovary cells is glycosylated much the same way as the erythropoietin present in human urine. To determine the role of carbohydrates in the stability of recombinant human erythropoietin in vivo, [125I]-labeled recombinant erythropoietin was intravenously infused into rats. The erythropoietin was slowly cleared from the blood with a half-life of approximately two hours. Asialoerythropoietin, which was produced by treatment of recombinant human erythropoietin with sialidase, was found to be cleared rapidly from circulation within ten minutes. These data suggest that the galactose binding protein of hepatic cells is involved in the clearance of asialoerythropoietin. Erythropoietin also contains N-glycans with a few N-acetyllactosamine repeats, which can be enriched by tomato lectin affinity chromatography. The lectin-bound fraction was cleared to a larger extent than was the unfractionated erythropoietin, while the component that did not bind the lectin was found to be stable in the circulation. Authentic N-acetyllactosamine repeats (polylactosaminoglycans) prepared from erythrocytes were similarly rapidly cleared from the circulation to the liver, and this clearance was inhibitable with asialo-alpha 1-acid glycoprotein. These results suggest that (a) the sialic acid of the recombinant erythropoietin is necessary for this glycoprotein hormone to circulate stably and (b) glycoproteins with more than three lactosaminyl repeat units may be cleared by the galactose binding protein of hepatocytes.

Purification of acetyllactosamine-specific tomato lectin by erythroglycan-sepharose affinity chromatography

Tomato lectin is specific for oligomers of poly-N-acetyllactosamine containing 3 repeating Gal(beta 1-4)GlcNAc (beta 1-3)-disaccharides. As such it is highly useful for purifying oligosaccharides or glycopeptides with poly-N-acetyllactosamine character. We have found the lectin very useful as an affinity reagent for isolating glycoproteins or glycoprotein domains having poly-N-acetyllactosamine glycosylation. Conventional preparation of tomato lectin by ovomucoid-Sepharose affinity chromatography was found to be unsatisfactory due to instability of column and bleeding of ovomucoid into eluents requiring the necessity for additional purification steps following affinity chromatography. We prepared a column of human erythrocyte band 3 carbohydrate glycopeptide (erythroglycan) attached to Sepharose as an affinity matrix. The purification of tomato lectin to homogeneity in one step on this column matrix is described in this report.

Spectrophotometric determination of hydrazine, hydrazides, and their mixtures with trinitrobenzenesulfonic acid

A method has been developed to measure hydrazine, hydrazides, and their mixtures using a modification of the trinitrobenzenesulfonic acid method [T. Okuyama and K. Satake (1960) J. Biochem. (Tokyo) 47, 654-660]. After incubation of the sample containing hydrazine and hydrazide with trinitrobenzenesulfonate at pH 8.5 at room temperature for 40 min, the reaction mixture was diluted with a Na2CO3-NaHCO3 buffer (0.1 M, pH 10.8) rather than with 0.5 M HCl. Different chromogens were produced from the reaction of hydrazine (lambda max = 570 nm) and hydrazides (lambda max = 385 and 500 nm) with trinitrobenzenesulfonic acid. The method allowed simultaneous determination of hydrazine (5 to 60 nmol) with hydrazide (10 to 120 nmol) in a mixture with a standard deviation of less than 5%. The presence of amino compounds (except for amino sugars) did not interfere with the measurement of hydrazine or hydrazides. Interference by amino sugars in the determination of hydrazine or hydrazides was eliminated by pretreatment of the sample with NaBH4 to reduce the amino sugars to 2-amino-2-deoxy-hexitols.

Lactosaminated Fab fragments specific for low density lipoproteins/hepatocyte targeting and hypolipoproteinemic activity

We have previously reported that Fab fragments of IgGs modified by lactosamination (lac-Fab) can direct macromolecules, including low density lipoproteins (LDL), to the liver. In the present paper we demonstrate that lac-Fab that is specific for LDL is an effective and selective hypolipoprotein agent. A plasma pool of about 60 mg/dl of apoprotein B (apo B) was induced in rats by bolus injection of human LDL (hLDL), which increased the cholesterol value to about 150 mg/dl. Three hours after injection of the highest dose of lac-Fab, the total cholesterol decreased to 80 mg/dl, compared to 120 mg/dl in control animals. Studies conducted with 131I-tyramine-cellobiose-labeled LDL indicated that the liver was the only organ in which lac-Fab increased LDL uptake and degradation. The effect of lac-Fab was dose-dependent. With amounts of lac-Fab between 13 to 42 mg/kg body weight, the amount of hLDL cleared through the lac-Fab mechanism ranged from 30% to 70% of the initial pool. Analysis of the plasma lipoprotein subfractions revealed that high density lipoprotein levels were not affected. Histologic examination of liver sections after sequential injection of fluorescently labeled hLDL and lac-Fab indicated specific uptake in the hepatocytes when compared to control sections obtained from animals injected with Dil-LDL alone. The uptake of fluorescent LDL induced by lac-Fab was completely prevented by a co-injection of an excess of asialofetuin. We conclude that lac-Fab that is specific for LDL is a selective hypolipoproteinemic agent and a specific carrier to the hepatocytes.

Serial polymers in the epidermis of Drosophila melanogaster larvae

The paper reports the existence of peculiar polymers (e-polymers) obtained from the epidermis of Drosophila melanogaster larvae. E-polymers result from the assembly of two components held together by alkali-labile bonds. Such components can be separated by CsCl density gradients and by DEAE-cellulose chromatography after controlled alkaline hydrolysis. One of the components contains predominantly neutral sugars and a phenolic substance (S-fraction). The other contains predominantly amino acids, aminosugars and a phenolic substance. This fraction can be visualized as serial multimers of a monomer subunit. It is suggested that e-polymers are continuous tridimensional structures which might have morphogenetic significance.

Oxygen radical generation by Maillard compounds

Amino sugars such as galactosamine are hepatotoxic. It has been verified that toxic hepatitis induced by galactosamine is similar to that of CCl4 poisoning, and that both were inhibited by O2* scavengers. Fructosamine results from the union of glucose with the epsilon-amine of lysine. A test for fructosamine quantification is based on nitroblue tetrazolium (NBT) reduction, in which O2- is involved, the reduction being inhibited in the presence of superoxide dismutase (SOD). Given these facts, we attempted to elucidate if galactosamine and glucosamine reduce NBT and if that reduction is inhibited by SOD. This was confirmed. Subsequently, we incubated aminoacids (glycine, lysine, alanine) with glucose and galactose for 7 days and studied the action of the incubation products on NBT, using amino acids and sugars as controls. We found that NBT reduction increases proportionally to the length of incubation time of glucose/galactose with lysine, but not with other amino acids. Reduction of NBT by the Amadori compounds formed is inhibited by SOD. We suggest that oxygen radical generation by Amadori compounds must be taken into consideration as one cause of damage in diabetes of long duration.

Isolation and structural characterization of an 8-O-(4-amino-4-deoxy-beta-L-arabinopyranosyl)-3-deoxy-D-manno- octulosonic acid disaccharide in the lipopolysaccharide of a Proteus mirabilis deep rough mutant

On short treatment of the lipopolysaccharide of a deep rough mutant of Proteus mirabilis (strain R45) with hydrochloric acid (0.01 M, 10 min, 100 degrees C) a compound was released which, on high-voltage paper electrophoresis, migrated slightly to the cathode (MGlcN = 0.19) and which stained with ninhydrin, alkaline silver nitrate and in the thiobarbituric acid assay. After purification and derivatization, its chemical structure was identified by combined gas-liquid chromatography/mass spectrometry and two-dimensional shift-correlated proton nuclear magnetic resonance spectroscopy as 8-O-(4-amino-4-deoxy-beta-L-arabinopyranosyl)-3-deoxy-D-manno-octu losonic acid. This disaccharide was also present in a wild-type strain of P. mirabilis.

Evidence for the presence of an N-acetyllactosamine-type chain in epiglycanin

Mannose-labeled epiglycanin was prepared by incubation of TA3-Ha ascites cells with [2-3H]mannose, removal of the epiglycanin by incubation of viable cells with L-1-p-tosylamino-2-phenylethyl chloromethyl ketone-trypsin, and isolation of the large epiglycanin glycopeptides by gel filtration. Purification of epiglycanin glycopeptides was performed by wheat germ agglutinin affinity chromatography. Extensive incubation of epiglycanin with Pronase, followed by passage through a calibrated column of Bio-Gel P-4 (Column P-4), gave three fractions. The fraction of lowest apparent molecular weight, about 5000, upon incubation with a purified extract from F. meningosepticum containing an N-glycosyl hydrolase and an endo-N-acetyl-beta-D-glucosaminidase (T.H. Plummer et. al. (1984) J. Biol. Chem. 259, 10700-10704) and passage through Column P-4 gave a peak of radioactivity at apparent Mr 3000. Incubation of nonlabeled epiglycanin under similar conditions with the same enzyme preparation followed by passage through Column P-4, gave two peaks, based upon total mannose content. One of these, partially deglycosylated epiglycanin, was present in the void volume. Its composition indicated that approximately 80% of the mannose content of epiglycanin had been removed by the enzyme treatment, whereas no change was noted in the proportion of the other carbohydrate components. The effluent volume of the second peak coincided precisely with the peak obtained from the Pronase-cleaved fraction. Its composition and apparent Mr were consistent with those of an N-lactosamine-type chain with four antennae, Man3Gal4GlcNAc5NeuAc2-3.

Antitumor activity and bone marrow toxicity of aminoglucose mustard anticancer agents in mice

In previous structure-activity studies, we have demonstrated that attachment of a glucose molecule to the chloroethylnitrosourea cytotoxic group produces a compound with reduced murine bone marrow toxicity and retention of full antitumor activity. To further define this protective role conferred by the glucose moiety in bone marrow cells, we have replaced the nitrosourea cytotoxic group with another class of alkylating agent, a bifunctional nitrogen mustard. In a detailed structure-activity analysis, we have now characterized four analogues, with the mustard cytotoxic group positioned at carbon 2 [1,3,4,6-tetra-O-acetyl-2-(di-2-chloroethyl)amino-2-deoxy-D-glucopyranos e (TGM)], carbon 6, or carbon 1 (D- and L-isomers) of the aminoglucose molecule. On a molar basis, TGM was most toxic to normal BALB/c X DBA/2 F1 mice, with a 10% lethal dose (LD10) of 3.8 mumol/kg. The D- and L-isomers of 2,3,4,6-tetra-O-acetyl-N,N-bis(2-chloroethyl)glucopyranosylamine (C-1) were the least toxic, with an LD10 of 73 mumol/kg for both. Optimal antitumor activity against the murine P388 leukemia (single i.p. administration of the LD10) did not differ significantly among the four analogues, with increased life span ranging from 83-86%. P388 antitumor activity for nitrogen mustard (HN2) was significantly less, 60% increased life span (P = 0.01), while p-di(2-chloroethyl)amino-L-phenylalanine produced an increased life span of greater than 101%. An LD10 of 6-bis-(2-chloroethyl) amino-6-deoxy-D-glucose (C-6) or TGM produced significantly less depression of WBC counts than did an equitoxic dose of the C-1 isomers, HN2, or p-di(2-chloroethyl)amino-L-phenylalanine. The mean nadir WBC count for C-6 equaled 86% of control, and for TGM, 80% of control. Consistent with this sparing effect on the peripheral WBC, C-6 and TGM produced significantly less in vivo murine bone marrow DNA synthesis depression, 77 and 64% of control, respectively, as compared to the depression nadir produced by HN2 (27% of control), the D-isomer of C-1 (17%), the L-isomer of C-1 (18%), and p-di(2-chloroethyl)amino-L-phenylalanine (2%). These structure-activity studies demonstrate that conjugation of the mustard cytotoxic group to carbon 6 or carbon 2 of glucose produces an analogue that retains P388 antitumor activity significantly greater than that of HN2, with a concomitant reduction in murine bone marrow toxicity.

Heterogeneous humoral and hemocyte-associated lectins with N-acylaminosugar specificities from the blue crab, Callinectes sapidus Rathbun

Callinectes sapidus serum and hemocyte microsomal fraction agglutinated a panel of untreated and enzyme treated vertebrate erythrocytes and cultured lymphoid cell lines. Crossed absorption experiments suggested the presence of multiple specific lectins in the serum. The microsomal fraction showed a 35-fold increase in specific activity when compared to the hemocyte lysate suggesting that hemocyte lectins are membrane-associated. Agglutination by serum and hemocyte lectins was inhibited by low concentrations of N-acylamino compounds including sialic, N-acetylmuramic and N-acetylglutamic acids, GalNAc, GlcNAc, ManNAc, and glycoproteins and polysaccharides which contain these carbohydrates: bovine submaxillary mucin, human orosomucoid, porcine stomach mucin and colominic acid. Hemagglutination by lectins of both serum and hemocyte microsomal fraction required divalent cations as suggested by the reduction in hemagglutination titer in the presence of the chelators EDTA, EGTA, CDTA and citrate.

Phospholipid vesicle targeting using synthetic glycolipid and other determinants

The interactions of carbohydrate-modified phospholipid vesicles with various isolated cell types in vitro have been studied to establish a better basis for understanding the mechanisms for recognition and transport of such modified vesicles in vivo. The physical basis for the use of perturbed angular correlation spectroscopy for the measurement of phospholipid vesicle integrity, and the kinetics of uptake of modified phospholipid vesicles by mouse peritoneal macrophage are first reviewed. The effects of variation of the chemical structure of the determinant and other factors indicate that the rate of uptake of cationic vesicles by mouse peritoneal macrophage is directly related to the distance that an amine group can be extended beyond the vesicle surface, and not, for example, to the stereochemistry of the carbohydrate determinant. The uptake mechanism appears to involve generalized phagocytosis and not a receptor-mediated mechanism, or an opsonization process that is not stereospecific.