Peptide differential

Dahlgren, K.N., Manelli, A.M., Stine, W.B., Jr., Baker, L.K., Krafft, G.A., and LaDu, M.J., Oligomeric and fibrillar species of amyloid-beta peptides differentially affect neuronal viability, J. Biol. Chem., 277, 32046, 2002. 

Yamaguchi, K. (2002). Peptide differential display of serum-free conditioned medium from cancer cell lines. Cancer Lett. 176, 199-203. 

Dahlgren KN, ManeUi AM, Stine WB Jr., Baker LK, Krafft GA, LaDu MJ (2002) Oligomeric and fibriUar species of amyloid-beta peptides differentially tiffect neuronal viabUity. J Biol Chem 277 32046-32053... 

Simantov R, Childers S. R., and Snyder S H. (1977) Opioid peptides, differentiation by radioimmunoassay and radioreceptor assay. Bram Res 135,358-367. 

The amide linkage between monomer units in a protein is called a peptide bond. Peptides and polypeptides, which often exhibit biological activity (see Antibiotics, peptides Neuroregulators), are smaller than proteins. Although the differentiation between polypeptide and protein is somewhat arbitrary, the usual distinction is drawn around 100 monomer units. Proteins are also characterized by higher levels of stmcture resulting from internal interactions. 

The gel-like, bead nature of wet Sephadex enables small molecules such as inorganic salts to diffuse freely into it while, at the same time, protein molecules are unable to do so. Hence, passage through a Sephadex column can be used for complete removal of salts from protein solutions. Polysaccharides can be freed from monosaccharides and other small molecules because of their differential retardation. Similarly, amino acids can be separated from proteins and large peptides. 

The mechanistic analogy to the Streckcr synthesis becomes obvious in the addition of the isocyanide to the imine to produce the a-amino nitrilium intermediate. Since all four components are involved in this step, it might be expected that every chiral component (chiral groups R1, R2, R3, R4) contributes to diastereofacial differentiation in the nucleophilic attack on the imine. However, in peptide syntheses by four-component condensation5, the chiral isocyanide or a chiral carboxylic acid component has only limited influence on the diastereoselectivity of the a-amino amide formation5. 

In the specialized environment of secondary lymphoid tissues such as lymph nodes or spleen, dendritic cells provide the requirements for naive T-lymphocytes to become activated and to proliferate. The professional antigen-presenting cells present peptides in MHC II, express costimulatory molecules, and release cytokines into the immunological synapse, which is formed by the antigen-presenting cell and the naive T-lymphocyte. Thus, cells of innate immunity initiate and facilitate the activation of naive lymphocytes, and it is easily conceivable that their cytokines and adhesion molecules will instruct the naive T-lymphocyte during activation and differentiation to T-effector cells. 

Like all neuropeptides, NT is synthesized as part of a larger precursor that also contains neuromedin N (NN), a 6 amino acid neurotensin-like peptide (Table 1). Pro-NT/NN is processed in the regulated secretory pathway of neuroendocrine cells by prohormone convertases PCI, PC2 and PC5-A that belong to a larger family of proprotein convertases. Due to differential cleavage specificity and tissue distribution of the convertases, pro-NT/NN processing gives rise to approximately a 1 1 and a 5 1 ratio of NT over NN content in the brain and gut, respectively. The peptides are stored in secretory vesicles and released from neuroendocrine cells in a Ca2+-dependent manner. NT and NN actions are terminated by desensitization of the... 

The predominant cell type in the pancreatic islets of Langerhans. The main secretory product of the (3 -cell is the peptide hormone insulin which has vital actions for the control of nutrient homeostasis and cellular differentiation. 

Peptide A linear chain of a small number of amino acids linked by peptide bonds. The number of amino acids which differentiates between a protein and a peptide remains a matter for discussion. 

Koppelhus U., Awasthi S.K., Zachar V., Holst H.U., Ebbesen P., Nielsen P. E. Cell-dependent differential cellular uptake of PNA, peptides, and PNA-pep-tide conjugates. Antisense Nucleic Acid Drug Dev. 2002 12 51-63. 

Hongmanee P., Stender H., Rasmussen O.F. Evaluation of a fluorescence in situ hybridization assay for differentiation between tuberculous and nontuberculous Mycobacterium species in smears of Low-enstein-Jensen and mycobacteria growth indicator tube cultures using peptide nucleic acid probes. J. Clin. Microbiol. 2001 39 1032-1035. 

Drobniewski E.A., More P.G., Harris G. S. Differentiation of Mycobacterium tuberculosis complex and nontuberculous mycobacterial liquid cultures by using peptide nucleic acid-fluorescence in situ hybridization probes./. Clin. Microbiol. 2000 38 444-447. 

B cells also have impact on T-cell differentiation. B-cell antigen presentation plays an important role at promoting Th2 responses and pathophysiology during allergic disorders. It has been shown that B-cell -/- mice and in mice selectively deficient in MHCII on B cells had decreased Th2 cytokines IL-4 and IL-5 [152]. Also in another study it has been reported that B-cell-derived exosomes can present allergen peptides and activate allergen-specific T cells to proliferate and produce Th2 cytokines IL-5 and IL-13 [42]. 

Semino CE, Merok JR, Crane GG et al (2003) Functional differentiation of hepatocyte-like spheroid structures from putative liver progenitor cells in three- dimensional peptide scaffolds. Differentiation 71 262-270... 

One peptide toxin from the mushroom Amanita phalhides, a-amanitin, is a specific differential inhibitor of the eukaryotic nuclear DNA-dependent RNA polymerases and as such has proved to be a powerful research tool (Table 37-2). a-Amanitin blocks the translocation of RNA polymerase during transcription. 

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