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2. Analysis of protein tyrosine phosphorylation by nanoelectrospray ionization high-resolution tandem mass spectrometry and tyrosine-targeted product ion scanning

Author

Salek, Mogjiborahman, Alonso, Angel, Pipkorn, R., and Lehmann, Wolf D.

Subjects
Chemistry, Analytic -- Research, Proteins -- Research, Chemistry
Abstract

A novel highly sensitive strategy is introduced for analysis of tyrosine phosphorylation in previously identified proteins channelling for this aim all analytical and sequence information available. Nanoelectrospray high-resolution MS/MS analysis is targeted to precalculated m/z values corresponding to phosphotyrosine-containing tryptic peptides. Identification of these peptides is supported by the occurrence of the phosphotyrosine immonium ion at m/z 216, neutral loss of 79.97/z (= loss of HP[O.sub.3]), and similarity of the fragmentation patterns of phosphotyrosine-containing peptides with their nonphosphorylated analogues. This tyrosine-targeted tandem mass spectrometry strategy is demonstrated for epidermal growth factor receptor showing that phosphotyrosine-containing tryptic peptides invisible in the survey spectrum can be safely identified.

Published
2003

16. Amide-based Disulfide Building Blocks for the Enlargement of the Solid Phase Peptide Synthesis for Molecular Diagnostics and Imaging

Author

Komljenovic D, Wiessler M, Pipkorn R, Braun K, Schrenk Hh, Fleischhacker H, Lorenz P, and Waldemar Waldeck

Subjects
business.industry, medicine.medical_treatment, Nanotechnology, Biology, Molecular diagnostics, Targeted therapy, chemistry.chemical_compound, chemistry, Proteome, Peptide synthesis, Nucleic acid, medicine, Personalized medicine, Molecular imaging, business, Linker
Abstract

Progress in genome and proteome research led to a deeper insight in differential gene expression processes. This required the use of sensitive and specific tools in diagnostics; also new promising patient-specific therapy attempts are conceivable. Nucleic acids were up till now a critical goal for diagnostic applications and therapeutic interventions, but in future they can serve as highly sequence-specific tools in molecular diagnostics. Examples for diagnostic Molecular Imaging modalities are the analysis of metabolic processes which can lead to customized therapeutic approaches (“Targeted Therapy”). The solid phase peptide synthesis SPPS is considered as an excellent tool in the individualized medicine with nucleic acids which increasingly play a key role as a drug. This requires new properties of the nucleic acid-based drugs, contiguous to the stability in biological systems, a high variability by combination with functional peptide-based molecules or with reformulated drugs or imaging components. The multifaceted application spectrum is dependent on the patients’ individual differential gene expression profiles or on the medical questionnaire. Here we show a new synthesis strategy able to circumvent ligations steps and to enhance the yields in the SPPS technology by use of a novel disulfide-containing monomer. This molecule acts as a disulfide linker which can overcome the common occasional losses occurring during established coupling reactions, like disulfide-bridge formations.

Published
2014
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17. Serological Evaluation of Possible Exposure to Ljungan Virus and Related Parechovirus in Autoimmune (Type 1) Diabetes in Children

Author

Nilsson, A-L, Vaziri-Sani, F., Broberg, P., Elfaitouri, A., Pipkorn, R., Blomberg, Jonas, Ivarsson, S-A, Larsson, H. Elding, Lernmark, A., Nilsson, A-L, Vaziri-Sani, F., Broberg, P., Elfaitouri, A., Pipkorn, R., Blomberg, Jonas, Ivarsson, S-A, Larsson, H. Elding, and Lernmark, A.

Abstract

Exposure to Ljungan virus (LV) is implicated in the risk of autoimmune (type 1) diabetes but possible contribution by other parechoviruses is not ruled out. The aim was to compare children diagnosed with type 1 diabetes in 2005-2011 (n=69) with healthy controls (n=294), all from the Jamtland County in Sweden, using an exploratory suspension multiplex immunoassay for IgM and IgG against 26 peptides of LV, human parechoviruses (HPeV), Aichi virus and poliovirus in relation to a radiobinding assay (RBA) for antibodies against LV and InfluenzaA/H1N1pdm09. Islet autoantibodies and HLA-DQ genotypes were also determined. 1) All five LV-peptide antibodies correlated to each other (P<0.001) in the suspension multiplex IgM- and IgG-antibody assay; 2) The LV-VP1_31-60-IgG correlated with insulin autoantibodies alone (P=0.007) and in combination with HLA-DQ8 overall (P=0.022) as well as with HLA-DQ 8/8 and 8/X subjects (P=0.013); 3) RBA detected LV antibodies correlated with young age at diagnosis (P<0.001) and with insulin autoantibodies (P<0.001) especially in young HLA-DQ8 subjects (P=0.004); 4) LV-peptide-VP1_31-60-IgG correlated to RBA LV antibodies (P=0.009); 5) HPeV3-peptide-IgM and -IgG showed inter-peptide correlations (P<0.001) but only HPeV3-VP1_1-30-IgG (P<0.001) and VP1_95-124-IgG (P=0.009) were related to RBA LV antibodies without relation to insulin autoantibody positivity (P=0.072 and P=0.486, respectively). Both exploratory suspension multiplex IgG to LV-peptide VP1_31-60 and RBA detected LV antibodies correlated with insulin autoantibodies and HLA-DQ8 suggesting possible role in type 1 diabetes. It remains to be determined if cross-reactivity or concomitant exposure to LV and HPeV3 contributes to the seroprevalence. J. Med. Virol. 87:1130-1140, 2015.

Published
2015
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18. Serological evaluation of possible exposure to Ljungan virus and related parechovirus in autoimmune (type 1) diabetes in children.

Author

Nilsson, Anna-Lena, Vaziri Sani, Fariba, Broberg, Per, Elfaitouri, A, Pipkorn, R, Blomberg, J, Ivarsson, Sten, Larsson, Helena, Lernmark, Åke, Nilsson, Anna-Lena, Vaziri Sani, Fariba, Broberg, Per, Elfaitouri, A, Pipkorn, R, Blomberg, J, Ivarsson, Sten, Larsson, Helena, and Lernmark, Åke

Abstract

Exposure to Ljungan virus (LV) is implicated in the risk of autoimmune (type 1) diabetes but possible contribution by other parechoviruses is not ruled out. The aim was to compare children diagnosed with type 1 diabetes in 2005-2011 (n = 69) with healthy controls (n = 294), all from the Jämtland County in Sweden, using an exploratory suspension multiplex immunoassay for IgM and IgG against 26 peptides of LV, human parechoviruses (HPeV), Aichi virus and poliovirus in relation to a radiobinding assay (RBA) for antibodies against LV and InfluenzaA/H1N1pdm09. Islet autoantibodies and HLA-DQ genotypes were also determined. 1) All five LV-peptide antibodies correlated to each other (P < 0.001) in the suspension multiplex IgM- and IgG-antibody assay; 2) The LV-VP1_31-60-IgG correlated with insulin autoantibodies alone (P = 0.007) and in combination with HLA-DQ8 overall (P = 0.022) as well as with HLA-DQ 8/8 and 8/X subjects (P = 0.013); 3) RBA detected LV antibodies correlated with young age at diagnosis (P < 0.001) and with insulin autoantibodies (P < 0.001) especially in young HLA-DQ8 subjects (P = 0.004); 4) LV-peptide-VP1_31-60-IgG correlated to RBA LV antibodies (P = 0.009); 5) HPeV3-peptide-IgM and -IgG showed inter-peptide correlations (P < 0.001) but only HPeV3-VP1_1-30-IgG (P < 0.001) and VP1_95-124-IgG (P = 0.009) were related to RBA LV antibodies without relation to insulin autoantibody positivity (P = 0.072 and P = 0.486, respectively). Both exploratory suspension multiplex IgG to LV-peptide VP1_31-60 and RBA detected LV antibodies correlated with insulin autoantibodies and HLA-DQ8 suggesting possible role in type 1 diabetes. It remains to be determined if cross-reactivity or concomitant exposure to LV and HPeV3 contributes to the seroprevalence. J. Med. Virol. © 2015 Wiley Periodicals, Inc.

Published
2015

24. The significance of molecular imaging for MRI in neuroradiology

Author

Heckl, S, Pipkorn, R, Nägele, T, Küker, W, and Voigt, K

Abstract

Molecular imaging with magnetic resonance imaging (MRI) is currently mainly focussed upon the representation of gene expression, the delineation of cell compartments, cell tracking and the display of extracellular structures. The majority of these methods are still at an experimental stage. The main points of interest in neuroradiology are the differentiation between tumor and non-tumor cells with the aid of oncogene profiles, the tracking of transplanted oligodendrocyte progenitor cells for the determination of the extent of remyelinization in the spinal cord and also the assessment of the therapeutic success in apoplexy using subventricular zone cells. New gadolinium contrast agents have enabled the depiction of β-amyloid plaques in Alzheimer's disease as well as showing the distribution of the endothelial leukocyte receptor ICAM-1 in acute experimental allergic encephalomyelitis (EAE).

Published
2003

38. Biological gene delivery and the local activation

Author

Corban-Wilhelm, H., primary, Braun, K., additional, Pipkorn, R., additional, Waldeck, W., additional, Spring, H., additional, Jenne, J., additional, Raster, R., additional, Simiantonakis, J., additional, and Debus, J., additional

Published
2001
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48. Peptide mimics of the vesicular stomatitis virus G-protein transmembrane segment drive membrane fusion in vitro.

Author

Langosch, D, Brosig, B, and Pipkorn, R

Abstract

The efficiency of cell-cell fusion mediated by heterologously expressed vesicular stomatitis virus G-protein has previously been shown to be affected by mutating its transmembrane segment. Here, we show that a synthetic peptide modeled after this transmembrane segment drives liposome-liposome fusion. Addition of millimolar Ca(2+) concentrations strongly potentiated the effect of the peptides suggesting that Ca(2+)-mediated liposome aggregation supports the activity of the peptide. Peptide-driven fusion was suppressed by lysolipid, an established inhibitor of natural membrane fusion, and involved inner and outer leaflets of the liposomal bilayer. Thus, transmembrane segment peptide-driven liposome fusion exhibits important hallmarks characteristic of natural membrane fusion. Importantly, the mutations previously shown to attenuate the function of full-length G-protein in cell-cell fusion also attenuated the fusogenicity of the peptide, albeit in a less pronounced fashion. Therefore, the function of the peptide mimic is dependent on its primary structure, similar to full-length G-protein. Together, our data suggest that the G-protein transmembrane segment is an autonomous functional domain. We propose that it acts at a late step in membrane fusion elicited by vesicular stomatitis virus.

Published
2001
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49. Presence of antibodies to a putatively immunosuppressive part of human immunodeficiency virus (HIV) envelope glycoprotein gp41 is strongly associated with health among HIV-positive subjects.

Author

Klasse, P J, Pipkorn, R, and Blomberg, J

Abstract

The IgG response to gp41 (envelope glycoprotein of Mr 41,000) of the human immunodeficiency virus (HIV) was studied with eight synthetic peptides derived from three different regions of the protein. We tested sera from 17 HIV-seronegative and 68 HIV-seropositive subjects in an enzyme immunoassay. No HIV antibody-negative serum reacted with any of the peptides. The peptide HIV-env 583-599 has a sequence similarity with immunosuppressive peptides derived from the transmembrane proteins of other retroviruses. Antibodies to this 17-mer (HIV-env 583-599; hereafter also referred to as pHIVIS, putative HIV immunosuppressive sequence) were detected in 27 of the 35 sera from healthy HIV-positive persons but only in 1 of the 33 sera from patients with HIV-related disease. Another 17-mer, displaced four amino acids N-terminally from pHIVIS, reacted with fewer of the sera from healthy seropositive subjects than pHIVIS but with no serum from ill seropositive patients. HIV-env 586-603, which shares two-thirds of its sequence with pHIVIS, reacted with the sera from nearly all subjects, regardless of clinical status. The remaining five peptides did not discriminate between healthy and ill seropositive subjects either but gave lower reactivity rates. HIV-positive sera thus exhibited distinct patterns of reactivity with subsequences of gp41. We have mapped two overlapping epitopes within a narrow part of gp41; antibodies to the most N-terminally located of the two--i.e., the pHIVIS-reactive antibodies--might counteract a possible immunosuppressive effect of gp41.

Published
1988
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