EuPA Open Proteomics最新文献

An MS/MS based analytical strategy was followed to solve the complete sequence of two new peptides from frog (Odorrana schmackeri) skin secretion. This involved reduction and alkylation with two different alkylating agents followed by high resolution tandem mass spectrometry. De novo sequencing was achieved by complementary CID and ETD fragmentations of full-length peptides and of selected tryptic fragments. Heavy and light isotope dimethyl labeling assisted with annotation of sequence ion series. The identified primary structures are GCD[I/L]STCATHN[I/L]VNE[I/L]NKFDKSKPSSGGVGPESP-NH₂ and SCNLSTCATHNLVNELNKFDKSKPSSGGVGPESF-NH₂, i.e. two carboxyamidated 34 residue peptides with an aminoterminal intramolecular ring structure formed by a disulfide bridge between Cys₂ and Cys₇. Edman degradation analysis of the second peptide positively confirmed the exact sequence, resolving I/L discriminations. Both peptide sequences are novel and share homology with calcitonin, calcitonin gene related peptide (CGRP) and adrenomedullin from other vertebrates. Detailed sequence analysis as well as the 34 residue length of both O. schmackeri peptides, suggest they do not fully qualify as either calcitonins (32 residues) or CGRPs (37 amino acids) and may justify their classification in a novel peptide family within the calcitonin gene related peptide superfamily. Smooth muscle contractility assays with synthetic replicas of the S–S linked peptides on rat tail artery, uterus, bladder and ileum did not reveal myotropic activity.

The harmonization of proteomics experiments facilitates the exchange and comparison of results. The definition of standards and metrics ensures reliable and consistent data quality. An internal quality control procedure was developed to assess the different steps of a proteomic analysis workflow and perform a system suitability test. The method relies on a straightforward protocol using a simple mixture of exogenous proteins, and the sequential addition of two sets of isotopically labeled peptides added to reference samples. This internal quality control procedure was applied to plasma samples to demonstrate its easy implementation, which makes it generic for most proteomics applications.

The aim of the present study was to create an optimal workflow for analysing a large cohort of malignant melanoma tissue samples. Samples were lysed with urea and enzymatically digested with trypsin or trypsin/Lys C. Buffer exchange or dilution was used to reduce urea concentration prior to digestion. The tissue digests were analysed directly or following strong cation exchange (SCX) fractionation by nano LC–MS/MS. The approach which resulted in the largest number of protein IDs involved a buffer exchange step before enzymatic digestion with trypsin and chromatographic separation in 120 min gradient followed by SCX–RP separation of peptides.

Bone marrow-derived human mesenchymal stem cells (BM-hMSCs) show promise as cell-based delivery vehicles for anti-glioma therapeutics, due to innate tropism for gliomas. However, in clinically relevant human-in-mouse glioma stem cell xenograft models, BM-hMSCs tropism is variable. We compared the proteomic profile of cancer and stromal cells in GSCXs that attract BM-hMSCs (“attractors”) with those to do not (“non-attractors”) to identify pathways that may modulate BM-hMSC homing, followed by targeted transcriptomics. The results provide the first link between fatty acid metabolism, glucose metabolism, ROS, and N-glycosylation patterns in attractors. Reciprocal expression of these pathways in the stromal cells suggests microenvironmental cross-talk.

The complete characterization of the snake venom protein components is a requirement for a systems-wide understanding of their biological context. In this work, we provide a deep proteomic characterization of Crotalus durissus terrificus venom using different bottom-up approaches. We identified more than five times more protein families than the sum of all identifications previously reported. For the first time in this sub-species, we report the identification of three new toxin families: CRISP, phospholipase-B, and SVVEGF. This work also describes proteins involved in regulation of toxin synthesis and processing that are present in venom.

Ten years ago, the first public proteomics repositories became available online. This anniversary is therefore an excellent occasion to look back on the past decade and evaluate what has changed in this time period. At the same time however, one should also dare to look forward, and therefore prepare for the next 10 years of proteomics data sharing.

The reproducibility of plasma protein quantitation between laboratories and between instrument types was examined in a large-scale international study involving 16 laboratories and 19 LC–MS/MS platforms, using two kits designed to evaluate instrument performance and one kit designed to evaluate the entire bottom-up workflow. There was little effect of instrument type on the quality of the results, demonstrating the robustness of LC/MRM-MS with isotopically labeled standards. Technician skill was a factor, as errors in sample preparation and sub-optimal LC–MS performance were evident. This highlights the importance of proper training and routine quality control before quantitation is done on patient samples.

The Proteopathogen database was the first proteomics online resource focused on experiments related to Candida albicans and other fungal pathogens and their interaction with the host. Since then, the HUPO-PSI standards were implemented and settled, and the first large scale C. albicans proteomics resource appeared as a C. albicans PeptideAltas. This has enabled the remodeling of Proteopathogen to take advantage and benefit from the use of the HUPO-PSI adopted format for peptide and protein identification mzIdentML and continue offering a centralized resource for C. albicans, other fungal pathogens and different cell lines proteomics data.

A targeted mass spectrometric assay was developed for identification and quantification of apoE isoforms (apoE2, E3 and E4), and it was utilized for screening of samples from AD patients (n = 39) and patients with other neurodegenerative disorders (n = 38). The assay showed good linearity with LOQ corresponds to total apoE concentration of 0.8 and 40 ng/mL in CSF and plasma/serum, respectively. We identified apoE phenotypes with 100% accuracy in clinical samples. We found strong association between genotypes of the individuals and their apoE levels in blood; ϵ4 allele carriers had significantly lower apoE levels in blood than non-carriers.