Effect of Protection Polymer Coatings on the Performance of an Amperometric Galactose Biosensor in Human Plasma

Galactose monitoring in individuals allows the prevention of harsh health conditions related to hereditary metabolic diseases like galactosemia. Current methods of galactose detection need development to obtain cheaper, more reliable, and more specific sensors. Enzyme-containing amperometric sensors based on galactose oxidase activity are a promising approach, which can be enhanced by means of their inclusion in a redox polymer coating. This strategy simultaneously allows the immobilization of the biocatalyst to the electroactive surface and hosts the electron shuttling units. An additional deposition of capping polymers prevents external interferences like ascorbic or uric acid as well as biofouling when measuring in physiological fuels. This work studies the protection effect of poly(2-methacryloyloxyethyl phosphorylcholine-co-glycidyl methacrylate (MPC) and polyvinylimidazole-polysulfostyrene (P(VI-SS)) when incorporated in the biosensor design for the detection of galactose in human plasma.

Co-immobilization of galactose oxidase, catalase, and Mn-superoxide dismutase for efficient conversion of 5-hydroxymethylfurfural to 2,5-diformylfuran in water

The three enzymes galactose oxidase (GO), catalase (CAT), and Mn-superoxide dismutase (SOD) were simultaneously immobilized by coordinating to CuII in phosphate buffer saline. The biocatalyst GO&CAT&SOD@CuII was used for the conversion of 5-hydroxymethylfurfural (HMF). The immobilized GO catalyzes the oxidation of HMF to 2,5-diformylfuran (DFF), concomitantly the co-substrate O2 is reduced to hydrogen peroxide (H2O2). A portion of the byproduct H2O2 is broken down to O2 and H2O by the co-immobilized CAT, and the evolved O2 can be recycled and used as the co-substrate. A portion of the byproduct H2O2 is broken down to produce hydroxyl radicals •OH under the synergistic catalysis of the immobilized SOD and coordinated CuII, and the produced •OH can reactivate the immobilized galactose oxidase. Two aspects contribute to the high catalytic efficiency by GO&CAT&SOD@CuII: the reactivation of the immobilized galactose oxidase by producing •OH and the enrichment of the co-substate O2 by recycling the produced O2. For the conversion of 10 mM HMF, GO&CAT&SOD@CuII (with encapsulated GO 0.2 mg/mL) achieved 97% HMF conversion within 2 h reaction. In contrast, free galactose oxidase M3-5 variant (ACS Catalysis 2018, 8, 4025) (0.2 mg/mL) achieved 25.3% HMF conversion within 2 h reaction. All the reactions were carried out in pure water, not in PBS.

Enzymatic Cascade for the Synthesis of 2,5-Furandicarboxylic Acid in Biphasic and Microaqueous Conditions: 'Media-Agnostic' Biocatalysts for Biorefineries

5-hydroxymethylfurfural (HMF) is produced upon dehydration of C6 sugars in biorefineries. As the product, it remains either in aqueous solutions, or is in situ extracted to an organic medium (biphasic system). For the subsequent oxidation of HMF to 2,5-furandicarboxylic acid (FDCA), 'media-agnostic' catalysts that can be efficiently used in different conditions, from aqueous to biphasic, and to organic (microaqueous) media, are of interest. Here, the concept of a one-pot biocatalytic cascade for production of FDCA from HMF was reported, using galactose oxidase (GalOx) for the formation of 2,5-diformylfuran (DFF), followed by the lipase-mediated peracid oxidation of DFF to FDCA. GalOx maintained its catalytic activity upon exposure to a range of organic solvents with only 1 % (v/v) of water. The oxidation of HMF to 2,5-diformylfuran (DFF) was successfully established in ethyl acetate-based biphasic or microaqueous systems. To validate the concept, the reaction was conducted at 5 % (v/v) water, and integrated in a cascade where DFF was subsequently oxidized to FDCA in a reaction catalyzed by Candida antarctica lipase B.

Galactose Oxidase Enables Modular Assembly of Conjugates from Native Antibodies with High Drug-to-Antibody Ratios

The potential of antibody conjugates with high drug loading in anticancer therapy has recently been highlighted by the approval of Trastuzumab deruxtecan and Sacituzumab govitecan. These biopharmaceutical approaches have spurred interest in bioconjugation strategies with high and defined degrees of drug-to-antibody ratio (DAR), in particular on native antibodies. Here, a glycoengineering methodology was developed to generate antibody drug conjugates with DAR of up to eight, by combining highly selective enzymatic galactosylation and oxidation with biorthogonal tandem Knoevenagel-Michael addition chemistry. This four-step approach offers a selective route to conjugates from native antibodies with high drug loading, and thus illustrates how biocatalysis can be used for the generation of biopharmaceuticals using mild reaction conditions.

Preparation of galactose oxidase functional phosphorescent quantum dots and detection of D-galactose

Environmental friendly nano biosensor can improve the detection performance of traditional biomolecular sensors and have important application value in practical applications. In this study, a kind of room temperature phosphorescence (RTP) quantum dots (QDs) (GOX RTP QDs) nanobiosensor was prepared by mineralization at room temperature (25 °C), using galactose oxidase (GOX) as template, which improved the catalytic ability of traditional GOx to D-Galactose. The specific enzyme substrate reaction between GOx and D-Galactose and photoinduced electron transfer (Piet) were used to detect the RTP of D-galactose. The linear range of D-galactose detection is 0.02-0.8 mM, and the detection limit of the method is 0.008 mM. This method is based on the RTP property of QDs, which can effectively avoid the interference of background fluorescence of biological samples, and does not need complex sample pretreatment process. Therefore, this method is more suitable for the quantitative detection of D-Galactose in biological samples.

One-Pot Enzyme Cascade for Controlled Synthesis of Furancarboxylic Acids from 5-Hydroxymethylfurfural by H2 O2 Internal Recycling

Furancarboxylic acids are promising biobased building blocks in pharmaceutical and polymer industries. In this work, dual-enzyme cascade systems composed of galactose oxidase (GOase) and alcohol dehydrogenases (ADHs) are constructed for controlled synthesis of 5-formyl-2-furancarboxylic acid (FFCA) and 2,5-furandicarboxylic acid (FDCA) from 5-hydroxymethylfurfural (HMF), based on the catalytic promiscuity of ADHs. The byproduct H₂ O₂ , which is produced in GOase-catalyzed oxidation of HMF to 2,5-diformylfuran (DFF), is used for horseradish peroxidase (HRP)-mediated regeneration of the oxidized nicotinamide cofactors for subsequent oxidation of DFF promoted by an ADH, thus implementing H₂ O₂ internal recycling. The desired products FFCA and FDCA are obtained with yields of more than 95 %.

Prospective evaluation of a novel approach for the use of a quantitative galactose oxidase-Schiff reaction in ductal fluid samples from women with breast carcinoma

BACKGROUND

The galactose oxidase-Schiff reaction (GOS) yields positive findings in a number of malignant solid tumors. The goals of the current study were to develop a novel technique for quantifying GOS reactivity in nipple aspirate fluid (NAF) samples from women with invasive breast carcinoma and to assess the clinical utility of the technique in this setting.

METHODS

Patients with biopsy-proven unilateral invasive breast carcinoma were eligible for study entry. Before definitive surgery, NAF samples were obtained from healthy breast tissue and malignant breast tissue from 23 women with breast carcinoma. Under blind conditions with respect to clinical data, 10 microL NAF samples were applied to a glass fiber membrane and incubated with 100 microL galactose oxidase and 1 mL Schiff reagent. The stain was developed and the color reaction quantitated by measuring hue (shade) and chroma (intensity) using a spectrophotometer.

RESULTS

GOS reactivity was quantitated using two color parameters, hue and chroma. Because chroma varies with concentration, this measurement was adjusted for the concentration of NAF in each sample. After adjustment for NAF concentration, chroma was found to be statistically significantly different in the affected breast tissue sample and the healthy contralateral internal control sample (P = 0.001).

CONCLUSIONS

A quantitative measure of GOS reactivity based on spectrophotometric measurement of intensity of color has been developed and was found to be significantly different in the affected breast compared with the unaffected breast in the current population of patients with breast carcinoma. The preliminary results support further exploration of this novel quantitative test in patients with breast carcinoma.

The footprint of antibody bound to pig cells: evidence of complex surface topology

The disaccharide Gal(alpha)1-3Gal is found on more than 45 different molecules on the endothelium of porcine cells and has recently attracted considerable interest, being the major target recognized by xenoreactive antibodies. In this study, the distribution and topology of Gal(alpha)1-3Gal on porcine endothelial cells was examined to access whether some Gal(alpha)1-3Gal-containing molecules might be preferentially recognized by antibodies binding to Gal(alpha)1-3Gal. Thirteen percent of the Gal(alpha)1-3Gal was found on glycolipid and 87% on glycoproteins. Of all the glycoproteins and glycolipids containing Gal(alpha)1-3Gal, two molecules, fibronectin and the integrin beta1 subunit, were most intensely labeled by galactose oxidase, suggesting that these molecules may be preferentially exposed on the apical surface of the endothelium. Binding of anti-Gal(alpha)1-3Gal antibodies to endothelial cell surfaces significantly diminished labeling of fibronectin and the integrin beta1 subunit by galactose oxidase, indicating that these glycoproteins are targets for the antibodies when binding to intact porcine cells.

Novel glucose non-interference biosensor for lactose detection based on galactose oxidase-peroxidase with and without co-immobilised beta-galactosidase

Two types of amperometric biosensors for lactose detection based either on co-immobilisation of two enzymes (galactose oxidase with peroxidase) or co-immobilisation of three enzymes (beta-galactosidase, galactose oxidase and peroxidase) were constructed. A graphite rod with pre-adsorbed ferrocene was used as a working electrode. The use of galactose oxidase instead of the frequently used glucose oxidase resulted in the construction of a glucose-non-interfering lactose sensor. Co-immobilisation of peroxidase with galactose oxidase allowed the effect of borate on the extension of the linear range and the effect of the working potential on galactose oxidase activation to be studied. The presence of beta-galactosidase greatly enhances the sensor's sensitivity, but its linear range is narrower than that of the sensor without beta-galactosidase. Addition of DEAE-dextran and inositol to the enzyme layer improved the half-life more than 16-fold compared with the sensor without stabilisers. A response time between 60 and 75 s (90% of the steady-state value) and a detection limit for lactose determination from 44 to 339 microM (signal-to-noise ratio = 3) were observed depending on the conditions. The precision of measurements of standard lactose solution for the trienzymatic and bienzymatic sensors was 2.19 and 2.02%, respectively. The precision of analysis of dairy products varied from 0.24 to 5.24%. Analyses of real samples showed good correlation with HPLC analysis; eight samples and 10 standard lactose solutions without pre-treatment were analysed in 1 h.

Determination of galactose and galactocerebroside using a galactose oxidase column and electrochemical detector

A method has been developed to measure galactose and galactocerebroside using galactose oxidase immobilized on a solid resin. Galactose oxidase converts galactose and galactocerebroside to their corresponding aldehydes and hydrogen peroxide, the latter being electroactive and measurable by electrochemical detection using DC amperometric detection. The minimal detection limits of galactose and galactocerebroside were 1 and 2 microM, respectively. The linear response to galactose and galactocerebroside was to at least 300 microM. About 100 samples can be measured per hour using flow injection analysis. The activity of sulfatidase (cerebroside-3-sulfate-3-sulfohydrolase), which converts sulfatide (sulfogalactocerebroside) to galactocerebroside, was measured, and its inhibition by O-phospho-L-tyrosine was determined.

Histochemical analysis of estrogen and progesterone receptors and gastric-type mucin in mucinous ovarian tumors with reference to their pathogenesis

BACKGROUND

Mucinous tumors of the ovary have been thought to originate in two ways: by müllerian-type metaplasia of surface epithelium, and as monodermal teratomas. To gain a better understanding of their pathogenesis, the authors analyzed these tumors for their expression of estrogen receptors (ER) and progesterone receptors (PR) as markers of müllerian-type differentiation and for their content of gastric-type mucin as a marker of gastric differentiation.

METHODS

The histochemical expression of ER, PR, and gastric-type mucin was studied in 10 specimens of the cervix with normal endocervical glands (as a representative of müllerian-derived mucin-containing cells), 3 ovary specimens with surface epithelial inclusion cysts that contained endocervical-like mucin-containing cells (representing müllerian-type metaplasia), and 47 mucinous tumors of the ovary (29 benign, 8 with low malignant potential, and 10 malignant).

RESULTS

Normal endocervical glands expressed ER and PR and rarely expressed gastric-type mucin. Ovarian inclusion cysts showed strong expression of ER and PR in the cuboidal cells and drastically reduced expression in the endocervical-like mucin-containing cells. The cuboidal cells were negative for gastric-type mucin, but the endocervical-like mucin-containing cells expressed gastric-type mucin. Endocervical-like mucinous cells in benign and borderline mucinous tumors showed expression of PR and/or gastric-type mucin in all cases.

CONCLUSIONS

The staining results for the inclusion cysts support the thesis that the endocervical-like mucinous cells encountered in the ones that express ER and PR weakly or not at all and have histochemical properties of normal gastric epithelium have their origin in metaplasia of müllerian-type epithelium. Application of the same staining methods to benign ovarian tumors and those with low malignant potential suggests strongly that similar müllerian-type metaplasia is a major pathway in their pathogenesis.

Validation of the galactose oxidase-Schiff's reagent sequence for early detection and prognosis in human colorectal adenocarcinoma

Based on the multistage and multifocal nature of colorectal carcinogenesis, it is likely that reduction of cancer mortality through early detection and identification of new prognostic markers is an attainable goal. Well-documented changes occur in mucin glycoconjugates during neoplastic progression in the colon, and the nonneoplastic colonic mucosa in colon cancer patients is morphologically and histochemically abnormal. In this retrospective study, 152 archival colorectal tissues from 49 patients were studied for changes in mucin secretions as detected by the galactose oxidase-Schiff's (GOS) sequence. Intensity of the stain was evaluated in histological sections by semiquantitative analysis, and the area percentage of epithelium stained was quantified by image cytometry. The correlation between gender or tumor size, location and reactivity with peanut agglutinin and quantitative expression of GOS-reactive mucins was determined as well as intratumor and inter individual variability. Reactivity with GOS: (a) decreased during neoplastic progression and malignant conversion in the neoplasm; (b) increased in the normal colonic mucosa of patients with progressively more advanced disease; and (c) was of prognostic significance for patient survival or recurrence both in the normal colon of cancer patients and in invasive neoplasms. These data are consistent with the conclusion that GOS reactivity in the normal colonic mucosa is a dosimeter of exposure to environmental/lifestyle colorectal carcinogens rather than a marker for an oncodevelopmental cancer-associated antigen.

[Clinical significance of galactose oxidase-Schiff reaction in the detection of carcinoma and precancerous lesions of large intestine]

OBJECTIVE

To study the clinical value of galactose oxidase-Schiff (GO-S) reaction to test carcinoma and precancerous lesions of large intestine.

METHODS

127 patients who had symptoms and signs of digestive tract diseases and 10 normal controls were studied, with their samples of rectum mucus smears stained. The histological sections of 73 cases of carcinoma and precancerous lesions of large intestine were stained with GO-S reaction.

RESULTS

The positive rates of GO-S reaction in carcinoma and precancerous lesions of large intestine were over 80%. The specificity and sensitivity of GO-S reaction to detect carcinoma and precancerous lesions of large intestine were 98% and 86%, respectively. The positive predictive value was 90%.

CONCLUSION

GO-S reaction, being satisfactory and sensitive marker of carcinoma and precancerous lesions of large intestine, can be used for screening and general survey of these lesions.

Trehalose as a possible precursor of the sulfated L-galactan in the ascidian tunic

Among sulfated polysaccharides, those in the tunic of ascidians are unique: their major constituent sugar is galactose, which occurs exclusively in the L-enantiomeric form. Incorporation of D-[14C]glucose into tunic slices in vitro revealed that the cells epimerize D-glucose into L-galactose during biosynthesis of the sulfated polysaccharides. The interconversion of these two sugars involves exchange of hydrogen atoms at the epimerization sites with protons of the medium. Tunic cells also synthesize trehalose, although this disaccharide is not a prominent constituent of the tissue. Pulse-chase experiments using D-[14C]glucose reveal that incorporation of label into trehalose precedes the synthesis of the sulfated L-galactan. In addition, the loss of label from trehalose coincides with the appearance of label in the sulfated L-galactan. Based on these results, we speculate that trehalose in the ascidian tunic may be a precursor of the sulfated L-galactan.

In situ accessibility of murine macrophage gangliosides

Gangliosides are implicated in cell signal transduction. Prior to investigating this phenomenon in macrophages, the in situ accessibility of gangliosides to macromolecules was assessed for peritoneal macrophages isolated from normal C3H/HeN and endotoxin-hyporesponsive C3H/HeJ mice. C3H/HeJ resident and thioglycolate-elicited macrophage ganglioside patterns are the same as normal strains, and no strain differences in galactose oxidase accessibility for resident or thioglycolate-elicited macrophage gangliosides were found. The only gangliosides accessible to galactose oxidase in resident macrophages are GM1a structures. In thioglycolate-elicited macrophages, an additional ganglioside is accessible. For Escherichia coli-activated macrophages, where ganglioside distribution differs between strains, a difference in galactose oxidase-accessible gangliosides also exists. Escherichia coli-activated C3H/HeN patterns show three triplets absent in C3H/HeJ patterns. There were no differences in ganglioside accessibility to Vibrio cholerae sialidase between the thioglycolate-elicited C3H/HeJ and C3H/HeN macrophages. However, despite differences in sialidase-sensitive ganglioside content between E.coli-activated macrophages of these strains, sialidase accessibility for E.coli-activated macrophages was also similar. Sialidase-susceptible GM3 was cryptic in either strain under all conditions examined. The accessibility of murine macrophage gangliosides to galactose oxidase or sialidase was independent of their sialic acid species and chain length of the ceramide fatty acid. With the exception of GM3, major murine macrophage gangliosides are accessible in situ to macromolecules, especially to exogenous pathogenic bacterial sialidase which can alter macrophage cell surface characteristics. Altered macrophage ganglioside accessibility appears sometimes as a consequence, but not a cause, of C3H/HeJ endotoxin hyporesponsiveness.

The formation of a dimeric product of raffinose by the action of galactose oxidase

1. Galactose oxidase is known to catalyze the oxidation of the C-6 hydroxymethyl group of galactose to an aldehyde group. 2. When the products of a galactose oxidase-catalase treatment of raffinose were examined by gel filtration and ion exchange chromatography, we found that in addition to the expected 6"-aldehydroaffinose, two other components were present. 3. One component was neutral and had an elution volume close to that of maltopentaose and on treatment with sodium borohydride or hypoiodite, this component was converted to raffinose or 6"-carboxyraffinose, respectively. 4. Fast atom bombardment mass spectroscopy in the negative mode indicated that the major molecular ion had an M/Z of 1003. 5. These data are consistent with this component being a dimer of 6"-aldehydoraffinose.

Comparison of Shams' test for rectal mucus to an immunological test for fecal occult blood in large intestinal carcinoma screening. Analysis of a check-up of 6480 asymptomatic subjects

The sugar moiety detected from rectal mucus by the Galactose oxidase-schiff (Shams' test) is considered a substitutive test for immunological fecal occult blood test (FOBT) in screening colorectal carcinoma. Two strategies of screening were applied in 6480 subjects over 40 years of age, and 130 cm flexible colonoscope used for sigmoidoscopy or pancolonoscopy. Of them, 3820 were taken for immune FOBT (SPA test) and Shams' test. Only those who showed positive tests were chosen for 60 cm flexible sigmoidoscopy, while another 2660 subjects for both sigmoidoscopy and tests at the same time. Additionally, 130 cm flexible pancolonoscopy was carried out in 103 individuals with positive Shams' test for evaluating the false positive rate. Shams' test showed a sensitivity of 85.7% for colorectal cancer, 47.1% for adenomas in preselected patients, while the positive rate of SPA test were 90.5% and 41.2% respectively. In 3820 asymptomatic subjects undergoing sequential screening (aged 45 years and higher), Shams' test showed 9.1% positive, SPA showed 11.2% and 620 (16.2%) subjects were selected for sigmoidoscopy based on their positive galactose oxidase result or positive FOBT result. Two early stage carcinomas and 33 adenomas (0.32% and 4.2% respectively in sigmoidoscopy) were found. Another 2 660 subjects were taken for sigmoidoscopy screening. Four carcinomas and 78 adenomas were found. Of them, only two carcinoma (50%) and 17 (21.8%) or 22 (28.2%) adenomas were positive in Shams' or SPA test. But both tests combined in screening showed a rate of 61.3% in adenomas and 75.0% in cancers. 103 subjects with positive Shams' test were taken for pancolonoscopy. 82.5% showed no lesions.(ABSTRACT TRUNCATED AT 250 WORDS)

A monoclonal antibody against carbohydrate moiety of rat gastric surface epithelial cell-derived mucin

A monoclonal antibody (MAb), designated RGM11, was generated against mucin purified from the surface epithelial layer of rat gastric mucosa. RGM11 reacted with the purified mucin which had been attached to the ELISA well. This reaction was inhibited by the oxidation of the ELISA well with periodate, indicating the carbohydrate moiety of the mucin molecule to be the epitope of RGM11. Treatment of the ELISA well with galactose oxidase also reduced the reaction with this MAb, thus suggesting the peripheral galactose and/or N-acetylgalactosamine residues of the carbohydrate moiety of mucin are involved in the epitope structure. Histochemical observation indicated that this MAb was able to stain the formalin fixed-paraffin embedded sections of rat and was positive to the surface mucous cells of corpus and antral region of the stomach and the villus epithelium of the duodenal mucosa, but other organs and tissues of rat so far examined were all negative to this MAb. These results indicate that this newly established MAb, labelled RGM11, might be useful to estimate the physiological changes in gastric surface mucous cells and the role of surface epithelial cell derived mucus in the gastric mucosal defense mechanisms.

Markers of surface mucous cell type human gastric cancer cells: galactose oxidase-Schiff reactive mucins, monoclonal antibody SH-9 reactive mucins and cathepsin E

Cellular differentiation of gastric cancer cells allows the classification of cell type into surface mucous cell, pyloric gland cell, intestinal absorptive cell and goblet cell types by mucin histochemistry and pepsinogen (Pg) immunohistochemistry. Surface mucous cell differentiation of gastric cancers of each histologic type has previously been detected by the galactose oxidase-Schiff (GOS) reaction although this is not always positive in all cases. Mucus granules of surface mucous cells of normal gastric mucosa show an intense reactivity for SH-9 (monoclonal antibody against CA125-bearing antigenic molecule fragments). Cathepsin E is also expressed in the cytoplasm of surface mucous cells, weakly in absorptive cells of duodenal villi and occasionally in pyloric gland cells. Expression of SH-9 reactive mucin and of cathepsin E were therefore investigated as possible additional markers to distinguish between the gastric cancer cell type in 203 primary stomach cancers. SH-9 reactive mucin was found selectively in GOS positive cancer cells of surface mucous cell type and/or cancer cells unclassified by mucin histochemistry. These latter cells were therefore classified into the surface mucous cell category. Cathepsin E was found mainly in cancer cells of the GOS positive surface mucous cell type and occasionally, in intestinal absorptive and pyloric gland cell types. Galactose oxidase-Schiff, SH-9 and cathepsin E reactive or positive cancer cells were found in 145 (71.4%), 151 (74.4%) and 144 (70.9%), respectively, of the 203 primary stomach cancers investigated.

Surface glycoconjugates of cynomolgus monkey trabecular cells

Non-ionic detergent-soluble and detergent-resistant cynomolgus monkey trabecular cell surface glycoconjugates have been identified using three radiolabeling procedures and polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. The cell surface glycoconjugates were radiolabeled with tritiated sodium borohydride after treatment with: (1) neuraminidase/galactose oxidase; (2) galactose oxidase; or (3) sodium metaperiodate. The non-ionic detergent soluble components were removed by treatment of the monolayer cell culture with 1% Triton X-100 in hypotonic buffer. The radiolabeled trabecular cell surface glycoconjugates in the Triton X-100 soluble and insoluble fractions were resolved by sodium dodecyl sulfate polyacrylamide gel electrophoresis under reducing conditions and visualized by fluorography. Treatment of the monkey trabecular cells with neuraminidase/galactose oxidase/tritiated sodium borohydride resulted in the radiolabeling of five components ranging in apparent molecular weight from 128,000 to 39,000 in the Triton X-100 soluble fractions, while 12 radiolabeled glycoconjugates with apparent molecular weights ranging from 240,000 to 26,000 were resolved in the Triton X-100 resistant fraction.

A high performance liquid chromatography method for the analysis of glycosphingolipids using galactose oxidase/NaB3H4 labeling of intact cells and synaptosomes

The major objective of this study was to combine an HPLC method with a galactose oxidase/NaB3H4 labeling method to allow both a chemical quantitation of individual glycolipids and analysis of their 3H labeling. Neutral glycolipids in whole cells were oxidized with galactose oxidase, and the resultant aldehydes were radiolabeled by reduction with tritiated sodium borohydride. Gangliosides, oxidized with galactose oxidase, either were reduced while in the native state in the whole cell or were first extracted and then reduced. Tritiated glycolipids were perbenzoylated and separated by HPLC. Ultraviolet detection of the derivatives was at 230 nm. Incorporated radioactivity was determined either by collecting fractions from the HPLC separation and counting on a liquid scintillation spectrometer or with a flow-through counter. The order of the derivatization and reduction is critical. Reduction of glycolipids prior to derivatization yielded sharp uv and radioactive peaks. Perbenzoylation of the oxidized glycolipids prior to reduction yielded multiple uv peaks, a noisy baseline, and broad radioactive peaks which did not always have a corresponding uv peak. The labeled neutral glycolipids were stable at -40 degrees C for at least 14 days, and gangliosides were stable at -15 degrees C for at least 14 days. When samples were stored at 20 degrees C there was a time-dependent decrease in the glycolipid/internal standard uv peak area ratio for GbOse4 and GbOse3 apparent by 28 days after perbenzoylation. The distribution of radiolabel among peaks showed no change with time or temperature. We adapted the technique to allow 3H labeling of glycolipids from monolayers of cultured glioma cells and from mouse brain synaptosomes.(ABSTRACT TRUNCATED AT 250 WORDS)

A dual staining method for identifying mucins of different gastric epithelial mucous cells

A dual staining method has been developed to identify two types of mucous secreting cells in the gastric mucosa of human and rat in one and the same tissue section. Sections were stained first using the galactose oxidase-cold thionin Schiff (GOCTS) procedure and then with paradoxical Concanavalin A staining (PCS). Surface mucous cell mucin stained blue with GOCTS, whereas gland mucous cell mucin stained brown with PCS. This method enabled us to differentiate these two types of mucins not only in gastric epithelial cell cytoplasm but also in the extracellular space. Sugar residues detected by GOCTS were explored by employing four species of lectins, which were peanut and Allomyrina dichotoma agglutinins for beta-galactose and Vicia villosa and Wistaria floribunda agglutinins for beta-N-acetylgalactosamine. The effect of oxidation with galactose oxidase was also examined on the affinities of reactive sites for these lectins. The results indicated that, in the human stomach, the sugar residues responsible for this reactivity were most likely beta-N-acetylgalactosamine and beta-galactose in specimens lacking secretion of blood group determinants and beta-N-acetylgalactosamine in those showing the secretion. In the rat stomach, on the other hand, sugar residues responsible for GOCTS were not elucidated by these lectins.

Enzymic oxidation of monoclonal antibodies by soluble and immobilized bifunctional enzyme complexes

Site-specific modification of monoclonal antibodies was achieved by oxidation of the carbohydrate moieties of antibodies which are located remote from the antigen binding sites. Sialic acid and galactose are terminal sugars of these carbohydrate chains. Concomitant treatment of the antibodies with neuraminidase and galactose oxidase generated aldehyde groups in the oligosaccharide moieties of immunoglobulins which reacted selectively with amino or hydrazide groups of the matrix. Subsequent immobilization of neuraminidase and galactose oxidase on Eupergit C-adipic dihydrazide proved to be an efficient and selective system for the enzymic oxidation of the monoclonal antibodies without impairing their immunological activity. Oriented immobilization of enzymically oxidized monoclonal antibodies on hydrazide or amino Eupergit C derivatives thus leads to the formation of antibody matrix conjugates which possess high antigen-binding activities.

Characterization of cytomegalovirus glycoproteins in a family of complexes designated gC-II with murine monoclonal antibodies

Several murine monoclonal antibodies (MoAbs) were made to a family of human cytomegalovirus (HCMV) disulfide linked glycoprotein complexes designated gC-II. Characterization of these MoAbs by immunological methods showed that they could be divided into two groups recognizing different glycoproteins. Western blot analysis was done with immunoaffinity purified gC-II complexes. Under non-reducing conditions MoAbs from both groups recognized gC-II complexes with molecular weights of 67-93 k and 130 k to greater than 200 k. When purified gC-II complexes were reduced and individual glycoproteins separated by SDS-PAGE prior to Western blotting, Group 1 MoAbs reacted with glycoproteins having molecular weights of 47-63k, while Group 2 MoAbs reacted with glycoproteins having molecular weights of 39-48k and 90k to greater than 200k. Thus, gC-II complexes contain glycoproteins recognized by both groups of MoAbs. By Coomassie blue staining and incorporation of [3H]Arg, Group 1 glycoproteins appeared to be minor components in the complexes relative to Group 2 glycoproteins. Surface labeling of extracellular virus with galactose oxidase and tritiated borohydride showed that gC-II complexes of all molecular weights were on the surface of the virus. However, the most heavily labeled gC-II glycoproteins had molecular weights of 47-63k. These data confirm our previous observations that the gC-II complexes of HCMV are comprised of a heterogeneous family of glycoproteins.

In vitro radiolabeling of galactosyl and N-acetylgalactosaminyl moieties of glycoproteins with carbon-14

The primary alcohol group on the carbon 6 of terminal galactosyl and N-acetylgalactosaminyl moieties of glycoproteins can be oxidized to an aldehyde by treatment with galactose oxidase. By reacting these aldehyde groups with 14C-labeled sodium cyanide, 14C-labeled cyanohydrin derivatives were obtained. Similarly, reduction of these aldehyde groups with tritiated sodium borohydride following standard procedures, yields 3H-labeled glycoproteins. 14C- and 3H-labeled derivatives of asialofetuin and asialo ovine submaxillary mucin with high specific radioactivities were prepared using these procedures. Mixtures containing microgram amounts of 14C- and 3H-labeled glycoproteins were subjected to column chromatography and gradient ultracentrifugation and the position of the individual glycoproteins was determined by simultaneous counting for 14C and 3H. These experiments demonstrate the usefulness of this approach for comparative analytical studies using biological specimens available in minute quantities.

Decreased accessibility of globotriaosylceramide associated with decreased tumorigenicity in Burkitt's lymphoma variants induced by immunoselection

To investigate a role for globotriaosylceramide (Gb3) as a tumor-associated antigen, variant cells resistant to treatment with complement and monoclonal antibody 38-13, which recognizes Gb3, were selected from a Burkitt's lymphoma cell line, Ramos. Variant cells displayed a clear decrease of antibody-binding capacity whereas the amount of Gb3 at their plasma membrane was not significantly different from that of Ramos parental cells. This demonstrated a reduced accessibility of Gb3 at the surface of variant cells. In parallel, no changes in other surface antigens were recorded as compared to those in Ramos cells. No changes of proliferative properties in suspension culture or of c-myc expression were observed although variant cells showed a decreased colony-forming capacity in agar. Variant cells showed a significant reduction in tumorigenic potential when injected s.c. into nude mice. The decreased tumorigenicity appeared related to the low antibody-binding capacity because both tumorigenicity and Gb3 antigenicity were recovered in parallel in revertant cells growing in suspension culture. In vivo, after two transplantations of variant cells into mice, cells isolated from the few induced tumors still retained the low antibody-binding capacity.

Requirement for both the CD3/T cell receptor complex and the CD2/lymphocyte function-associated antigen-3 adhesion system in monocyte-independent T cell activation by oxidized erythrocytes

Recent reports have shown that human T lymphocytes can be activated in vitro by desialyzed oxidized erythrocytes (DOE) in a monocyte-independent fashion. These findings suggest that, in addition to providing the activating stimulus, DOE may also fulfill accessory cell roles normally supplied by monocytes in T cell activation. DOE may thus be a useful substitute for antigen-presenting accessory cells in studies of T cell activation. This report describes experiments conducted to determine if T cell activation by DOE involves cell surface structures known to play a role in antigen-induced T cell activation. T cell stimulation by DOE was blocked by anti-CD3 monoclonal antibody, suggesting that perturbation of the CD3/T cell antigen receptor complex on T cells is required for activation. Activation was also blocked by anti-CD2 monoclonal antibody, indicating involvement of the CD2/LFA-3 adhesion system. Since DOE and monocytes both express LFA-3, the role of LFA-3 on DOE in T cell activation was assessed. DOE pretreated with anti-LFA-3 monoclonal antibody induced markedly lower levels of T cell proliferation. As further evidence for LFA-3 involvement, DOE prepared from 5 patients with paroxysmal nocturnal hemoglobinuria (PNH), known to exhibit deficient LFA-3 expression, were also deficient in T-cell stimulatory activity. These findings illustrate that T cell activation by DOE requires many of the surface structures involved in activation by antigen-bearing accessory cells, and may thus serve as a useful model for studies of T cell activation.

Modification of galactose and N-acetylgalactosamine residues by oxidation of C-6 hydroxyls to the aldehydes followed by reductive amination: model systems and antifreeze glycoproteins

Amino acids and peptides have been attached to the C-6 hydroxyls of the galactose and the N-acetylgalactosamine by first oxidizing the C-6 hydroxyls to the aldehydes by galactose oxidase in the presence of small amounts of catalase, followed by reductive amination (alpha-amino group) in the presence of cyanoborohydride. The activity of oxidized antifreeze glycoprotein was greater than 70% of the original, and considerable activity has been retained with some substitutions on reductive amination using cyanoborohydride. The following were some activities retained (as compared with the oxidized antifreeze glycoprotein): Gly, 64; (Gly)2, 88; (Gly)3, 82; (Gly)4, 70; Gly-Gly-NH2, 44; Gly-Glu, 13; Gly-Leu, 40; Gly-Tyr, 57; Gly-Gly-Leu, 50; Gly-Gly-Phe, 30; and Gly-Gly-Val, 35. On amino acid analysis of acid hydrolysates, some release of the amino acid attached by amination occurred; e.g., Gly-Tyr gave 0.26 Gly and 0.49 Tyr per disaccharide.

A carbohydrate histochemical study on surface mucous cells, mucous neck cells and chief cells in the gastric mucosa of developing mice

The ontogenesis of the mouse gastric mucosa was studied by carbohydrate histochemistry and 3H-thymidine autoradiography. Surface mucous cells and glandular cells were identified from day 16 of gestation. Sugar residues in the mucin of surface mucous cells seem to undergo no major changes throughout the period under study, since secretory granules of the cells were positive in periodic acid-Schiff (PAS) and galactose oxidase-Schiff (GOS) reactions and consistently bound certain lectins. Chief cells and mucous neck cells are not separated until the third postnatal week, though primitive chief cells are present during earlier developmental stages. Secretory granules of primitive chief cells shared positive PAS and GOS reactions with mucous neck cells and bound similar lectins, but the intensity was generally weaker. The granules of primitive chief cells were also stained by Bowie's solution which exclusively stained zymogen granules in chief cells in adults. These results suggest that secretory granules of primitive chief cells contain a complex carbohydrate similar to mucin in mucous neck cells, but with a lower sugar/protein ratio. It is concluded by studies using 3H-thymidine autoradiography combined with carbohydrate histochemistry that, though immature surface mucous cells, primitive chief cells and mucous neck cells actively proliferate, chief cells rarely undergo mitosis.

Oxidation of glycolipids in liposomes by galactose oxidase

Small unilamellar phosphatidylcholine vesicles containing globo-series glycolipids were labeled by the galactose oxidase/NaB[3H]4 procedure. The major glycolipid of human red cells, globoside, was the best substrate for galactose oxidase both in vesicles and in tetrahydrofuran-containing buffer. The oxidation rates of membrane-bound ceramide trihexoside and Forssman glycolipid were one-fourth and one-tenth, respectively, of the oxidation rate of globoside. Membrane-bound ceramide dihexoside was not a substrate for galactose oxidase, although it was readily oxidized in tetrahydrofuran-containing buffer. Soluble sialoglycoproteins and membrane-incorporated glycophorin A stimulated the oxidation of globoside-containing vesicles, whereas membrane-bound GD1a ganglioside had no effect on globoside oxidation.

A trial of alloreactive T-cell depletion using biotinylated galactose oxidase for the prevention of acute graft-versus-host diseases

Galactose oxidase was labelled onto the surface of mitomycin-C treated splenic lymphocytes from BALB/C mice (H-2d, Mlsb). Mouse splenic lymphocytes from DBA/2 (H-2d, Mlsa) mixed with the galactose oxidase labelled BALB/C lymphocytes allowed DBA/2 cells which recognized the Mlsb on the BALB/C cells to make direct contact with the galactose oxidase labelled BALB/C cells. By adding galactose, sodium iodide and catalase to the mixture, the contacting stimulator cells will generate hydrogen peroxide in the vicinity of the contacting responder cells and the iodine ions will exert a toxic effect on the responder cells while non-specific cytotoxicity was prevented by catalase. When fresh mitomycin-C treated BALB/C lymphocytes were added to the cell mixture, the mixed lymphocyte response against BALB/C cells by the treated DBA/2 lymphocytes was abolished. On the other hand, when fresh mitomycin-C treated lymphocytes from C57BL/6 mice (H-2b, Mlsb) were mixed with the treated DBA/2 cells, the mixed lymphocyte response against C57BL/6 cells by the treated DBA/2 lymphocytes was partially retained. Therefore, although some non-specific cytotoxicity was present, a method to deplete specific T-lymphocytes that recognize major histocompatibility antigen from a mixed cell population while maintaining immune responsiveness towards other antigens was developed. This method may have a beneficial effect on the control of post-transplant immunity and may be used as a prophylaxis of graft-versus-host disease.

Light microscopic characterization of glycoconjugates in secretory cells of the carp (Cyprinus carpio) gill epithelium

Secretory products of granular and mucous cells in the gill epithelium of the carp, Cyprinus carpio, were distinguished by their cytochemical reactions with peroxidase-labelled lectins and with the galactose oxidase (GO)-Schiff reagents. Secretory products of granular cells reacted with lectins from Triticum vulgaris (WGA), Arachis hypogaea (PNA), Dolichos biflorus (DBA), Glycine max (SAB), and Lotus tetragonolobus (LTA). They also reacted with GO-Schiff reagents. After sialic acid cleavage with HCl, new binding sites for DBA and SBA appeared, suggesting the terminal sequence sialic acid-N-acetylgalactosamine (SA-GalNAc) for the secretion of this cell type. In mucous cells, binding sites for WGA, DBA, and SBA and, after acid hydrolysis, binding sites for PNA and a positive GO-Schiff reaction were detected. The terminal trisaccharide sialic acid-galactose (beta 1-3)-N-acetylgalactosamine (SA-Gal-GalNAc) is proposed for the secretion of mucous cells. These cytochemical differences are discussed in light of the involvement of both cell types in fish mucus elaboration.

B lymphoblastoid cell lines with normal and defective O-glycosylation established from an individual with blood group Tn

Individuals with the Tn blood group contain terminal serine/threonine-linked N-acetylgalactosamine residues in their blood cells. This is due to lack of UDP-D-galactose: D-N-acetyl galactosamine beta-D-galactosyl transferase from part of their red cells and probably from their leukocytes. We have established B lymphoblastoid cell lines from such an individual by in vitro infection of his lymphocytes with Epstein-Barr virus. The original line contained a mixture of cells reactive and nonreactive with Helix pomatia lectin (Hp). These cells were subcloned after staining with fluorescent Hp by a fluorescence-activated cell sorter (FACS) into homogeneous, phenotypically stable lines of Hp-positive (Hp+) and Hp-negative (Hp-) cells. The molecular differences between the membrane glycoproteins were characterized by carbohydrate-specific surface labeling techniques, Hp affinity chromatography, polyacrylamide slab gel electrophoresis and glycopeptide/oligosaccharide analysis. The major O-glycosidic membrane glycoprotein (GP105) was retained on Hp-Sepharose columns only from Hp+ cells, whereas the common leukocyte antigen (GP160-200) was partially retained on Hp columns from both lines. These proteins were isolated by immune precipitation with monoclonal antibodies and characterized. The results show that the GP105 glycoprotein from Hp+ cells contains terminal N-acetylgalactosamine residues but also more complex oligosaccharides. The common leukocyte antigen showed different electrophoretic mobilities in Hp+ and Hp- cells. UDP-galactose D-N-acetyl galactosamine beta-galactosyl transferase was almost absent in the Hp+ cells. These cell lines are useful for studies on the functional role and regulation of the biosynthesis of O-glycosidic carbohydrates.

Specific tritium labeling of glucosyl- and galactosylceramides at the 6-position of the carbohydrate moiety using CrO3-graphite

A new procedure for introducing tritium into the carbohydrate portions of glucosyl- and galactosylceramides was developed using a new catalyst, CrO3-graphite, which specifically oxidizes the primary alcohol group to the aldehyde. About 10% of the glycolipid was converted to the aldehyde and the aldehyde produced was then reduced back to the original form with KB3H4. After methanolysis, more than 96.7% of the radioactivities of [3H]glucosyl- and [3H]galactosylceramides were found to be located in the carbohydrate portions, and the specific activities of the [3H]galactosyl- and [3H]glucosylceramides were 2.08 to 4.30 X 10(4) cpm/nmol, which could be increased greatly by purifying the aldehydes and reducing them with KB3H4. In addition, beta-galactosidase activity was successfully determined with [3H]galactosylceramide as the enzyme substrate; the Km was 18.73 mM and the Vmax was 11.63 nmol/mg/h, indicating that no significant structural modification occurs during the oxidation.

Galactose oxidase-Schiff reaction and lectin stainings

Thirty-four cases of carcinoma of the human large intestine were studied employing a battery of histochemical techniques to identify and characterize mucosubstances, including galactose oxidase-Schiff (GOS) reaction and stainings with horseradish peroxidase-labeled lectins. The results disclosed that the goblet cell-type mucin (GCM) of the left colon differed from that of the right colon in containing 8-O-acetylated N-acetylneuraminic acid (NANA) more abundantly and 8-O-acetylated NANA-(alpha Fuc)-beta Gal type terminal structures. The right colonic GCM, on the other hand, was shown to contain alpha Fuc-beta Gal type predominantly. Surface coat-type mucin (SCM) showed consistent histochemical reactivities regardless of the sites in the large intestine. The transitional mucosa surrounding carcinoma tissues characteristically revealed decreased sulfation and neuraminidase-induced GOS reactivity, suggesting the presence of NANA-beta Gal type terminals. The carcinoma tissues resembled the transitional mucosa in showing neuraminidase-induced GOS reactivity, but differed from the latter in possessing intense UEA-I reactivity. The present study indicated that the refined histochemical techniques recently developed were quite useful for understanding the histochemical reactivities correlating with sugar structures.

Solid-phase radiolabeling of glycolipids with galactose oxidase and sodium boro[3H]hydride

Neutral glycosphingolipids immobilized on plastic surfaces were specifically radiolabeled with the galactose oxidase-sodium boro[3H]hydride method. Glycolipids could be immobilized in the absence of any other lipids such as phosphatidylcholine and cholesterol. Rather, the presence of these lipid components decreased the efficiency of radiolabeling. Glycolipids having more than four carbohydrate moieties with terminal galactosyl residues were effectively radiolabeled and could be easily recovered by elution from the plastic with ethanol in one step. This method will be suitable for analysis of small samples of "upper-phase" neutral glycolipids having terminal galactose or N-acetylgalactosamine.

Characterization of plasma-membrane glycoproteins from functional domains of the rat hepatocyte

Plasma-membrane glycoproteins from the three different functional domains of the rat hepatocyte were radioactively labelled by oxidation with NaIO4, followed by reduction with NaB3H4. Analysis of the radioactively labelled glycoproteins by polyacrylamide-gel electrophoresis revealed the presence of at least 12 major sialoglycoproteins in each different region of the hepatocyte surface. The Mr-110 000 component was homogeneously distributed over the plasma membrane, whereas the Mr-90 000 polypeptide was only located at the sinusoidal face. These radiolabelled glycoproteins were solubilized in 1% Triton X-100, and the soluble fraction was subjected to affinity chromatography on Sepharose-conjugated wheat-germ agglutinin (WGA). The labelled glycoproteins were poorly bound to WGA. Membrane glycoproteins were also labelled by the galactose oxidase/NaB3H4 method. The results show that the polypeptides with apparent Mr 170 000 from the sinusoidal, 230 000 from the canalicular and 170 000 from the lateral membranes were specifically labelled. When the membranes were treated with neuraminidase and galactose oxidase/NaB3H4, the electrophoretic patterns showed changes in the apparent Mr values of the glycoproteins, owing to loss of sialic acid, and a clear increase in labelling in the sinusoidal and canalicular membranes compared with the lateral membranes. When these labelled membranes were solubilized in 1% Triton X-100 and subjected to affinity chromatography on Sepharose-conjugated Ricinus communis agglutinin and/or Lens culinaris agglutinin, the results showed that the former columns efficiently bound the radiolabelled glycoproteins, whereas the latter columns bound poorly. The results show that there is a differential distribution of glycoproteins along the hepatocyte's surface.

Galactose-rich glycoproteins are on the cell surface of herpes virus-infected cells. 1. Surface labeling and serial lectin binding studies of Asn-linked oligosaccharides of glycoprotein gC

Cell-surface glycoproteins of mock-infected and herpes simplex virus type 1 (HSV-1)-infected BHK-21 and HEp-2 cells were radiolabeled by incubation with galactose oxidase followed by reduction with NaB3H4. The incorporation of radiolabel into glycoconjugates in both BHK-21 and HEp-2 cells was increased several fold following infection with HSV, showing an increase in surface-exposed Gal residues in the infected cells. This was further confirmed by an increase in binding of cell-surface-labeled glycoproteins gC and gB from HSV-infected BHK-21 cells to Ricinus communis agglutinin I, which is specific for beta-D-Gal residues. Prior treatment of cells with Clostridium perfringens neuraminidase enhanced the surface radiolabeling by the galactose oxidase/NaB3H4 method: HEp-2 cells exhibited over sixfold enhancement in labeling, while BHK-21 cells showed only a slight increase. HSV glycoprotein gC was the predominant cell-surface glycoprotein radiolabeled by the galactose oxidase/NaB3H4 method in virus-infected BHK-21 cells. The glycoprotein gC was purified by immunoaffinity column chromatography on monoclonal anti-gC-antibody-Sepharose. The radiolabel in the glycopeptides of gC was resistant to beta elimination, showing that it was associated only with Asn-linked oligosaccharides. A serial lectin affinity chromatography of glycopeptides on columns of concanavalin A-Sepharose, lentil (Lens culinaris) lectin-Sepharose, and Ricin I-agarose allowed the assignment of minimal oligosaccharide structures bearing terminal Gal residues in gC.