ABSTRACT
The pentapetide thymopentin (TP5) corresponding to the aminoacids RKDVY represents the residues 32-36 of thymopoietin (TP), which was originally isolated from bovine thymus. Both were observed to induce T-cell differentiation and maturation. Recently however it was shown, that TP represents the N-terminal 49 aa of the human thymopoietin (TMPO) isoforms TMPO alpha, beta and gamma, which are localized in the nucleus. TP5 was investigated in a variety of diseases and showed efficacy by improving the immune balance, whereby different cells increased in cell number or activity. Findings which support the assumption of multifunctional efficacy and a description of TP and TP5 modulating T cells lack any interpretation on molecular level. In the present study we investigated the binding of TP5 on white blood cells. We identified monocytes and neutrophils as TP5-binding cells by displacing fluorescein-labelled TP5 with an excess of unlabelled TP5 in competition assays. Binding of TP5 on cell surface proteins resulted in cellular signalling and we report here that TP5 triggers signal transduction involving mitogen activated protein kinases p42/p44 (MAPKs) in monocytes.
Subject(s)
Adjuvants, Immunologic/metabolism , Adjuvants, Immunologic/pharmacology , Calcium-Calmodulin-Dependent Protein Kinases/metabolism , Mitogen-Activated Protein Kinases , Monocytes/drug effects , Monocytes/metabolism , Thymopentin/metabolism , Thymopentin/pharmacology , Animals , Cattle , Flow Cytometry , Fluoresceins , Fluorescent Dyes , Granulocytes/drug effects , Granulocytes/immunology , Granulocytes/metabolism , Humans , In Vitro Techniques , Mitogen-Activated Protein Kinase 1/metabolism , Mitogen-Activated Protein Kinase 3 , Monocytes/immunology , Signal Transduction/drug effectsABSTRACT
Bioactivity-guided fractionation of a CH2Cl2 extract from the leaves of Piper aduncum afforded three new dihydrochalcones, piperaduncins A [3], B [4], and C [5], as well as two known dihydrochalcones, 2',6'-dihydroxy-4'-methoxydihydrochalcone [1] and 2',6',4-trihydroxy-4'-methoxydihydrochalcone [2] (asebogenin), together with sakuranetin, anodendroic acid methyl ester, and the carotenoid lutein. The structures of the isolates were elucidated by spectroscopic methods, mainly 1D- and 2D nmr spectroscopy. The proposed stereochemistry for compound 4 was deduced by NOESY spectroscopy and the corresponding energy minimum was established by molecular modelling calculations and translated into a 3D structure.
Subject(s)
Anti-Bacterial Agents/isolation & purification , Antineoplastic Agents, Phytogenic/isolation & purification , Chalcone/analogs & derivatives , Plants, Medicinal/chemistry , Animals , Anti-Bacterial Agents/pharmacology , Antineoplastic Agents, Phytogenic/pharmacology , Bacillus subtilis/drug effects , Biomphalaria , Chalcone/isolation & purification , Chalcone/pharmacology , Chalcones , Chromatography, Thin Layer , Computer Simulation , Drug Screening Assays, Antitumor , Escherichia coli/drug effects , Humans , KB Cells/drug effects , Magnetic Resonance Spectroscopy , Microbial Sensitivity Tests , Micrococcus luteus/drug effects , Models, Molecular , Molecular Conformation , Molluscacides/isolation & purification , Molluscacides/toxicity , New Guinea , Plant Extracts/chemistry , Plant Extracts/pharmacologyABSTRACT
The preferred solution conformation of the PRP-hexapeptide (Tyr-Val-Pro-Leu-Phe-Pro) and of some of its structural analogues was investigated by NMR-spectroscopy, spectrofluorimetry and computer simulation technic. It was found that the preferred conformation is characterized by cis'-conformation of Pro3 and the gamma-turn on the Leu4-residue: for Val2 and Phe5 a beta-structure seems to be privileged. In such a conformation Val2 and Leu4 residues occupy exactly the same positions in space as residues i and i + 3 in an alpha-helix. It suggests that the PRP-hexapeptide can interact with receptor protein inducing or stabilizing its helical conformation by "knobs into holes" packing.