Unusual N-type glycosylation of salivary prolactin-inducible protein (PIP): multiple LewisY epitopes generate highly-fucosylated glycan structures.

Prolactin-inducible protein (PIP) is a glycoprotein found in body secretions from exocrine glands like saliva and seminal plasma. Important biological functions of PIP concentrations have been demonstrated, e.g. in tumor diagnosis and progression. PIP quantity has been also found useful to determine the success of chemotherapy of mammary carcinoma. Here, we present the analysis of the N-glycosylation of PIP isolated from different sources by LC-MS(/MS) and 1H-NMR. We found a very uncommon N-type glycosylation of PIP in healthy individuals from both, seminal fluid and saliva. PIP carries unusual highly fucosylated N-linked glycans with multiple Lewisy (Ley) epitopes on bi-, tri- and tetraantennary structures resulting in up to nine fucosyl residues on a tetraantennary glycan. In most organs, Ley epitopes are not present on N-glycans except in case of a tumor when it is highly up-regulated and important for prognosis. Here, for the first time on a specific glycoprotein Ley antigens are unambiguously characterized on an N-type glycan by NMR spectroscopy. So far, for specific glycoproteins Ley epitopes had only been reported on O-glycans. Furthermore, a correlation between a nonsynonymous single nucleotide polymorphism (SNP) and glycosylation pattern was detected: individuals heterozygous for the SNP causing the amino acid exchange 51Gln to 51His have glycan structures with a higher degree of sialylation compared to individuals lacking the SNP.

Hadamard-Transform Fluorescence Excitation-Emission-Matrix Spectroscopy.

We present a fluorescence excitation-emission-matrix spectrometer with superior data acquisition rates over previous instruments. Light from a white light emitting diode (LED) source is dispersed onto a digital micromirror array (DMA) and encoded using binary n-size Walsh functions ("barcodes"). The encoded excitation light is used to irradiate the liquid sample and its fluorescence is dispersed and detected using a conventional array spectrometer. After exposure to excitation light encoded in n different ways, the 2-dimensional excitation-emission-matrix (EEM) spectrum is obtained by inverse Hadamard transformation. Using this technique we examined the kinetics of the fluorescence of rhodamine B as a function of temperature and the acid-driven demetalation of chlorophyll-a into pheophytin-a. For these experiments, EEM spectra with 31 excitation channels and 2048 emission channels were recorded every 15 s. In total, data from over 3000 EEM spectra were included in this report. It is shown that the increase in data acquisition rate can be as high as [{n(n + 1)}/2]-fold over conventional EEM spectrometers. Spectral acquisition rates of more than two spectra per second were demonstrated.

Glycan analysis of Prostate Specific Antigen (PSA) directly from the intact glycoprotein by HR-ESI/TOF-MS.

Glycans are important modulators of the biological function of proteins and are normally characterized from proteolytic glycopeptides or from (N-)glycans released enzymatically by glycosidase treatment or chemically by hydrazinolysis. We demonstrate that glycan compositions can easily be determined directly by LC-ESI/TOF-MS from intact glycoproteins even with a very complex glycosylation pattern. Interpretation of isotopically resolved mass spectra of prostate specific antigen (PSA) using bioinformatics tools gives within a few hours the glycan compositions of 38 glycoforms.

Tumor-associated Neu5Ac-Tn and Neu5Gc-Tn antigens bind to C-type lectin CLEC10A (CD301, MGL).

In human tumors, glycoproteins often exhibit abnormal glycosylation patterns, e.g. certain Lewis structures, TF antigen, Tn antigen and/or their sialylated forms, creating additional binding sites for glycoreceptors. In the present study, we have analyzed the carbohydrate specificity of the C-type lectin CLEC10A using glycan profiling by enzyme-linked immunosorbent assay (ELISA). In addition to the known ligands, we show binding to two tumor-associated antigens, namely Neu5Acα2,6-Tn and Neu5Gcα2,6-Tn, with an affinity of CLEC10A in the micromolar range. Detailed analyses of the glycan-lectin interactions were carried out by surface plasmon resonance (SPR) and saturation transfer difference (STD) NMR. CLEC10A binds Neu5Acα2,6-Tn and Neu5Gcα2,6-Tn with dissociation constants of 297 and 80 µM, respectively, as determined by SPR. Comparison of the STD nuclear magnetic resonance (NMR) binding epitopes of Tn and Neu5Acα2,6-Tn revealed a constant binding mode of the N-acetylgalactosamine moiety. This finding is in good agreement with binding studies of CLEC10A transfectomas, which show a well-defined interaction of transmembrane CLEC10A with 6-sialylated-Tn structures. Since both Neu5Acα2,6-Tn and Neu5Gcα2,6-Tn together with the previously known Tn antigen are expressed in human tumors such as mammary carcinoma, the interaction with CLEC10A expressed by macrophages and dendritic cells could be of major functional significance in tumor progression.

Glycan analysis: scope and limitations of different techniques--a case for integrated use of LC-MS(/MS) and NMR techniques.

The structure of glycans from glycoproteins is highly relevant for their function. We tightly integrate liquid chromatography-mass spectrometry (LC-MS), MS/MS, and nuclear magnetic resonance (NMR) data to achieve a complete characterization of even isobaric glycans differing in only one linkage position or in the substitution in one branch. As example, we analyzed ten desialylated underivatized glycans from bovine fibrinogen. The molecules were separated on a PGC column, and LC-MS data allowed an assignment of the compositions of the glycans. MS/MS data of the same glycans allowed elucidation of sequence and to some extent of branching and linkage. All MS/MS fragmentation methods led to multiple dissociations, resulting in several cases in ambiguous data. The MS/MS data were interpreted both by scientists and automatically by software, and the differential results are compared. Additional data from a tight integration of LC-MS and NMR data resulted in a complete structural characterization of the glycans. The acquisition of simple 1D (1)H NMR data led--in combination with LC-MS and MS/MS data--to an unambiguous assignment of the isobaric glycans. Compounds that were not separated in the chromatography could easily be assigned structurally by applying the 3D cross-correlation (3DCC) technology to arrive at NMR spectra of the pure components-without actually separating them. By applying LC-MS, MS/MS, 1D (1)H NMR, and 3DCC together, one can assign glycan structures from glycoconjugates with high confidence affording only 200 pmol of glycan material.

Dolutegravir quantification in wistar rat tissues following chronic administration.

Dolutegravir (DTG) has been introduced into first line combination antiretroviral therapy (ART) for HIV/AIDS. Penetration of ART into HIV reservoirs is essential to prevent continuous replication of HIV. However, accumulation of DTG in HIV reservoirs could be contributing to the adverse effects reported. We have developed and applied liquid chromatography tandem mass spectrometry (LC-MS/MS) methods to quantify DTG in wistar rat biological matrices following chronic DTG administration. DTG was detected using a Shimadzu 8040 triple quadrupole-mass spectrometer. The methods developed were in the concentration ranges of 17.5-8000 ng/mL for plasma and 15.5-16 680 ng/g for tissue matrices. Mean plasma DTG concentrations in the current study closely corresponded to plasma DTG levels reported in humans after chronic treatment. Plasma and tissue DTG concentrations were generally higher in females compared to male wistar rats, but these differences were nullified after correcting for body and organ size. Plasma DTG levels correlated with tissue DTG concentrations in the liver and gastrocnemius muscle tissue. Data suggest that body size - rather than sex - may be a major risk factor determining adverse outcomes of patients on the current DTG dosing strategy which does not account for differences in body mass. Furthermore, plasma DTG was not correlated with adipose tissue DTG concentration. This suggests that adipose may be a primary site for longer term inflammatory dysregulation and adverse outcome following DTG treatment.

Glycosylation assists binding of HIV protein gp120 to human CD4 receptor.

The role of glycosylation of proteins on its binding affinity is not well understood. Even a monosaccharide (magenta) placed at a glycosylation site can significantly enhance binding of peptides to their receptor. If glycosylated, an HIV protein binds stronger and faster to its primary receptors on human cells.

Resolving the problem of chromatographic overlap by 3D cross correlation (3DCC) processing of LC, MS and NMR data for characterization of complex glycan mixtures.

Chromatographic overlap is a common problem in the analysis of complex mixtures. As a result, it is not possible to identify the components because each resulting NMR or MS spectrum contains multiple components. We introduce three-dimensional cross correlation (3DCC) that dissects NMR spectra of a mixture into spectra of the individual components without actually separating them. Correlation of peaks from MS and NMR profiles along a common LC time domain yields 3DCC NMR spectra of pure components correlated with a mass and a retention time. The method requires an LC run followed by fractionation and recording of MS and NMR spectra. The method is applicable to mixtures of any classes of molecules. Here, we demonstrate its application to a mixture of complex glycans obtained from a glycoprotein. Fourteen glycans eluting within only 3 min showed heavy overlap in the chromatographic run. 3DCC allowed their direct characterization without separation. Some of these structures from the glycoprotein bovine fibrinogen had not previously been described. The 3DCC procedure has been implemented in standard software. Actually, 3DCC can be used for any combination of separation techniques, like LC or GC, combined with two characterization methods like UV, IR, Raman, NMR or MS.

Rooibos (Aspalathus linearis) alters secretome trace amine profile of probiotic and commensal microbes in vitro.

ETHNOPHARMACOLOGY RELEVANCE: Aspalathus linearis (Burm.f.) R. Dahlgren (rooibos) tea is anecdotally renowned for its calming effect in the context of gastrointestinal discomfort, but little scientific support is available to elucidate potential mechanisms of action. Enhancement of dietary polyphenol content to improve gut health via prebiotic-like modulation of the gut microbiota has gained significant research interest. Given the known high polyphenol content of rooibos, rooibos tea may potentially exert a prebiotic effect in the gut to facilitate an improvement in chronic inflammatory gastrointestinal conditions. AIM OF THE STUDY: This study aimed to determine the prebiotic or health-modulating potential of rooibos tea in terms of its effect on gut microbial growth and secretome trace amine composition, as well as to determine how differential rooibos processing alters this activity. METHODS: Three rooibos preparations (green and fermented leave aqueous extracts, as well as a green leaf ethanol extract) were compared in terms of their phenolic composition (qTOF-LC/MS). Moreover, the effect of rooibos exposure on growth and secretome trace amine levels of probiotic and commensal microbes were assessed (LC/MS). In addition, given the known female bias prevalent for many gastrointestinal disorders, experiments were conducted in the absence and presence of estradiol. RESULTS: Polyphenolic composition of rooibos was drastically reduced by fermentation. Aqueous extracts of both green and fermented rooibos improved microbial growth, although fermented rooibos had the most pronounced effect (p < 0.01). In terms of secretome trace amine profile, both aqueous extracts of rooibos seemed to facilitate increased putrescine secretion (p < 0.0001) and decreased tryptamine production (p < 0.0001). Estradiol seemed to suppress trace amine secretion by bacteria (Lactobacillus plantarum, Lactobacillus reuteri and Enterococcus mundtii) but increased it in yeast (Saccharomyces boulardii). CONCLUSION: Rooibos altered gut probiotic and commensal microbial growth and secretome trace amine profiles in vitro, suggesting it has potential to modulate gut microbial composition and functionality as a prebiotic. Current data suggest that these effects are highly dependent on raw material processing. Finally, rooibos may be able to prevent estradiol-associated alterations in trace amine profile, which may have important implications for patient management in female-predominant gastrointestinal disorders.

Biotransformation of Dimethenamid-P by the basidiomycete Irpex consors.

Twenty-nine basidiomycetes were screened in surface and liquid cultures for their capability to biotransform the chloroacetamide herbicide Dimethenamid-P (DMTA-P). The basidiomycete Irpex consors converted 70% of the herbicide (0.5 g L-1 DMTA-P) in liquid cultures within 6 days, applying a minimal medium under non-ligninolytic conditions. Nine transformation products of DMTA-P were identified by liquid chromatography-mass spectrometry analysis of the culture supernatants. The four main metabolites were isolated and subjected to GC-MS analysis and NMR spectroscopy. The analyses revealed that the thiophene ring was oxidized at three different positions. Metabolite M1 was identified as the S-oxide, which was isolable and relatively stable at room temperature. In metabolite M2, one methyl substituent of the thiophene ring was hydroxylated. The two metabolites M3A and M3B were diastereomers, but fully separated by HPLC. Here, oxidation of the aromatic CH carbon resulted in prototropic rearrangement to an αß-unsaturated thiolactone. None of the three major metabolites of DMTA-P has been described before.

Electrochemical treatment of iopromide under conditions of reverse osmosis concentrates--elucidation of the degradation pathway.

Application of reverse osmosis for the reuse of treated wastewater on the one hand offers a way to provide high quality effluent waters. On the other hand reverse osmosis concentrates exhibiting highly concentrated contaminants are produced simultaneously. Electrochemical treatment of those concentrates is regarded as one possible answer to the problem of their disposal into surface waters. Nevertheless, due to the diversity of direct and indirect degradation processes during electrolysis, special care has to be taken about the formation of toxic transformation products (TPs). In this study the electrochemical transformation of the X-ray contrast medium iopromide was investigated as a representative of biologically persistent compounds. For this purpose, anodic oxidation at boron doped diamond as well as cathodic reduction using a platinum electrode were considered. Kinetic analyses revealed a transformation of 100 µM iopromide with first order kinetic constants between 0.6 and 1.6 × 10(-4) s(-1) at the beginning and a subsequent increase of the reaction order due to the influence of secondary oxidants formed during electrolysis. Mineralization up to 96% was achieved after about 7.5 h. At shorter treatment times several oxidatively and reductively formed transformation products were detected, whereas deiodinated iopromide represented the major fraction. Nevertheless, the latter exhibited negligible toxicological relevance according to tests on vibrio fisheri. Additional experiments utilizing a divided cell setup enabled the elucidation of the transformation pathway, whereas emerging TPs could be identified by means of high resolution mass spectrometry and MS(n)-fragmentations. During electrolysis the iodine released from Iopromide was found to 90% as iodide and to 10% as iodate even in the open cell experiments, limiting the potential formation of toxic iodo-disinfection by-products. Chlorinated TPs were not found.

Formation of the immunogenic α1,3-fucose epitope: elucidation of substrate specificity and of enzyme mechanism of core fucosyltransferase A.

Glycans of glycoproteins are often associated with IgE mediated allergic immune responses. Hymenoptera venoms, e.g., carry α1,3-fucosyl residues linked to the proximal GlcNAc of glycoproteins. This epitope, formed selectively by α1,3-fucosyltransferase (FucTA), is xenobiotic and as such highly immunogenic and it also shows cross-reactivity if present on different proteins. Production of post-translationally modified proteins in insect cells is however commonly used and, thus, resulting glycoproteins can carry this highly immunogenic epitope with potentially significant side effects on mammals. To analyze mechanism, specificity and reaction kinetics of the key enzyme, we chose FucTA from Apis mellifera (honeybee) and characterized it by saturation transfer difference (STD) NMR and surface plasmon resonance (SPR) experiments. Specifically, we show here that the donor substrate, GDP-Fucose, binds mostly via its guanine and less so via pyrophosphate and fucosyl fragments and has a K(D) = 37 µM. Affinity and kinetic studies with both the core α1,6-fucosylated and the unfucosylated octa- or heptasaccharides, respectively, as acceptor substrate revealed that honeybee FucTA prefers the latter structure with affinities of K(D) âˆ¼ 10 mM. Establishment of progress curve analysis using an explicit solution of the integrated Michaelis-Menten equation allowed for determination of key constants of the transfer reaction of the glycosyl residue. The dominant minimum acceptor substrate is an unfucosylated heptasaccharide with K(m) = 420 µM and k(cat) = 6 min(-1). Time-resolved NMR spectra as well as STD NMR allow molecular insights into specificity, activity and interaction of the enzyme with substrates and acceptors.

[Management of biceps tendon ruptures with the "key hole-plasty"]. / Die Versorgung von Bicepssehnenrupturen mit der "Schlüssellochplastik".

This is a report about 18 cases of a rupture of the long proximal biceps tendon. The interligamentous, "closed" lesion like an elongation was cured by gathering up the tendon (3 patients). With very good results 15 cases of a typical rupture in the sulcus intertubercularis were operated by using the so called "keyhole plasty". This method should be favoured.