Purification and characterization of riproximin from Ximenia americana fruit kernels.

Highly pure riproximin was isolated from the fruit kernels of Ximenia americana, a defined, seasonally available and potentially unlimited herbal source. The newly established purification procedure included an initial aqueous extraction, removal of lipids with chloroform and subsequent chromatographic purification steps on a strong anion exchange resin and lactosyl-Sepharose. Consistent purity and stable biological properties were shown over several purification batches. The purified, kernel-derived riproximin was characterized in comparison to the African plant material riproximin and revealed highly similar biochemical and biological properties but differences in the electrophoresis pattern and mass spectrometry peptide profile. Our results suggest that although the purified fruit kernel riproximin consists of a mixture of closely related isoforms, it provides a reliable basis for further research and development of this type II ribosome inactivating protein (RIP).

Toward protein biomarkers for allergy: CD4+ T cell proteomics in allergic and nonallergic subjects sampled in and out of pollen season.

Allergy is an immunological disorder of the upper airways, lung, skin, and the gut with a growing prevalence over the last decades in Western countries. Atopy, the genetic predisposition for allergy, is strongly dependent on familial inheritance and environmental factors. These observations call for predictive markers of progression from atopy to allergy, a prerequisite to any active intervention in neonates and children (prophylactic interventions/primary prevention) or in adults (immunomodulatory interventions/secondary prevention). In an attempt to identify early biomarkers of the "atopic march" using minimally invasive sampling, CD4+ T cells from 20 adult volunteers (10 healthy and 10 with respiratory allergies) were isolated and quantitatively analyzed and their proteomes were compared in and out of pollen season (± antigen exposure). The proteome study based on high-resolution 2D gel electrophoresis revealed three candidate protein markers that distinguish the CD4+ T cell proteomes of normal from allergic individuals when sampled out of pollen season, namely Talin 1, Nipsnap homologue 3A, and Glutamate-cysteine ligase regulatory protein. Three proteins were found differentially expressed between the CD4+ T cell proteomes of normal and allergic subjects when sampled during pollen season: carbonyl reductase, glutathione S-transferase ω 1, and 2,4-dienoyl-CoA reductase. The results were partly validated by Western blotting.

Identification of glycoprotein receptors within the human salivary proteome for the lectin-like BabA and SabA adhesins of Helicobacter pylori by fluorescence-based 2-D bacterial overlay.

Because gastric infection by Helicobacter pylori takes place via the oral route, possible interactions of this bacterium with human salivary proteins could occur. By using modified 1- and 2-D bacterial overlay, binding of H. pylori adhesins BabA and SabA to the whole range of salivary proteins was explored. Bound salivary receptor molecules were identified by MALDI-MS and by comparison to previously established proteome maps of whole and glandular salivas. By use of adhesin-deficient mutants, binding of H. pylori to MUC7 and gp-340 could be linked to the SabA and BabA adhesins, respectively, whereas binding to MUC5B was associated with both adhesins. Binding of H. pylori to the proline-rich glycoprotein was newly detected and assigned to BabA adhesin whereas the SabA adhesin was found to mediate binding to newly detected receptor molecules, including carbonic anhydrase VI, secretory component, heavy chain of secretory IgA1, parotid secretory protein and zinc-alpha(2)-glycoprotein. Some of these salivary glycoproteins are known to act as scavenger molecules or are involved in innate immunity whereas others might come to modify the pathogenetic properties of this organism. In general, this 2-D bacterial overlay technique represents a useful supplement in adhesion studies of bacteria with complex protein mixtures.

Fungal secretomes--nature's toolbox for white biotechnology.

Adapting their metabolism to varying carbon and nitrogen sources, saprophytic fungi produce an arsenal of extracellular enzymes, the secretome, which allows for an efficient degradation of lignocelluloses and further biopolymers. Based on fundamental advances in electrophoretic, chromatographic, and mass spectrometric techniques on the one hand and the availability of annotated fungal genomes and sophisticated bioinformatic software tools on the other hand, a detailed analysis of fungal secretomes has become feasible. While a number of reports on ascomycetous secretomes of, e.g., Aspergillus, Trichoderma, and Fusarium species are already available, studies on basidiomycetes have been mainly focused on the two model organisms Phanerochaete chrysosporium and Coprinopsis cinerea so far. Though an impressive number and diversity of fungal biocatalysts has been revealed by secretome analyses, the identity and function of many extracellular proteins still remains to be elucidated. A comprehensive understanding of the qualitative and quantitative composition of fungal secretomes, together with their synergistic actions and kinetic expression profiles, will allow for the development of optimized enzyme cocktails for white biotechnology.

Proteome analysis of glandular parotid and submandibular-sublingual saliva in comparison to whole human saliva by two-dimensional gel electrophoresis.

The secretions of the salivary parotid and submandibular-sublingual (SMSL) glands constitute the main part of whole human saliva (WS) in which proline-rich proteins (PRPs) and mucins represent dominant groups. Although proteome analysis had been performed on WS, no identification of PRPs or mucins by 2-DE and MS was achieved in WS and no comprehensive analysis of both glandular secretions is available so far. The aim of this study was to compare the protein map of WS to parotid and SMSL secretions for the display of PRPs and mucins. WS and glandular secretions were subjected to 2-DE and spots were analyzed by MALDI-MS. New components identified in WS were cyclophilin-B and prolyl-4-hydroxylase. Also acidic and basic PRPs as well as the proline-rich glycoprotein (PRG) could now be mapped in WS. Acidic PRPs were found equally in parotid and SMSL secretions, whereas basic PRPs and PRG were found primarily in parotid secretion. Salivary mucin MUC7 was identified in SMSL secretion. Thus, the more abundant proteins of WS can be explained mainly by mixed contributions of parotid and SMSL secretions with only few components remaining that may be derived from local sources in the oral cavity.

Application of proteomics and protein analysis for biomarker and target finding for immunotherapy.

Regulatory T-cells play a central role in the maintenance of the immunological balance and are powerful inhibitors of T-cell activation both in vivo and in vitro. The enhancement of suppressor-cell function might be a target for immunotherapeutic approaches for the treatment of immune-mediated diseases like multiple sclerosis and Crohn's disease.The method of choice to elucidate the still unclear effector functions of regulatory T-cells is the differential proteome analyses performed with human and murine T-cell populations. To this end, whole-protein extracts of conventional and regulatory T-cells are separated by high-resolution two-dimensional gel electrophoresis according to Klose. The proteomes are analyzed by a 2DE gel image analysis software, ProteomWeaver. The protein spots that are found differentially expressed are picked from the gels and prepared for matrix-assisted laser desorption/ionization (MALDI) mass spectrometrical analysis automatically. The high-resolution 2DE-PAGE and the automated spot handling and protein identification allows one to rapidly find new potential candidate proteins that are of functional relevance for regulatory T-cells, to be used as targets for drug development or as biomarkers for research and diagnostic purposes.

Sequence dependent fragmentation of peptides generated by MALDI quadrupole time-of-flight (MALDI Q-TOF) mass spectrometry and its implications for protein identification.

A study has been undertaken to evaluate the usefulness of MALDI Q-TOF data for protein identification. The comparison of MS data of protein digests obtained on a conventional MALDI TOF instrument to the MS data from the MALDI Q-TOF reveal peptide patterns with similar intensity ratios. However, comparison of MS/MS Q-TOF data produced by nanoelectrospray versus MALDI reveals striking differences. Peptide fragment ions obtained from doubly charged precursors produced by nanoelectrospray are mainly y-type ions with some b-ions in the lower mass range. In contrast, peptide fragment ions produced from the singly charged ions originating from the MALDI source are a mixture of y-, b- and a-ions accompanied by ions resulting from neutral loss of ammonia or water. The ratio and intensity of these fragment ions is found to be strongly sequence dependent for MALDI generated ions. The singly charged peptides generated by MALDI show a preferential cleavage of the C-terminal bond of acidic residues aspartic and glutamic acid and the N-terminal bond of proline. This preferential cleavage can be explained by the mobile proton model and is present in peptides that contain both arginine and an acidic amino acid. The MALDI Q-TOF MS/MS data of 24 out of 26 proteolytic peptides produced by trypsin or Asp-N digestions were successfully used for protein identification via database searching, thus indicating the general usefulness of the data for protein identification. De novo sequencing using a mixture of 160/18O water during digestion has been explored and de novo sequences for a number of peptides have been obtained.