RESUMEN
The influence of short protein fragments on immobilization stress-induced alterations in neuroendocrine and immune systems (catecholamine content in the striatum, hypothalamus and adrenals, serum corticosterone concentration, specific antibody producing activity) was investigated. Immunoglobulin G fragments--tuftsin, rigin, polar amino acid set--polarin and thymus hormone fragment--thymopoetin, as well as substance P (as reference drug) were administered intraperitoneally at doses of 100 and 500 micrograms/kg 30 min before exposure to stress. Rigin and thymopentin showed high stress-protective activity. It is suggested that similar protein fragments, being endogenously formed, may play a regulating role in neuroimmunological homeostasis during exposure to stress.
Asunto(s)
Adyuvantes Inmunológicos/uso terapéutico , Neurotransmisores/uso terapéutico , Oligopéptidos/uso terapéutico , Estrés Fisiológico/prevención & control , Animales , Inmovilización , Masculino , Fragmentos de Péptidos/uso terapéutico , Ratas , Estrés Fisiológico/etiología , Timopentina , Timopoyetinas/uso terapéutico , Tuftsina/uso terapéuticoRESUMEN
The binding of angiotensin II and its analogues (13) to rabbit antibodies and glomerular cell receptors from rat adrenal cortex was studied, using the radioimmunoassay method and radioreceptor analysis. Double modifications introduced into the angiotensin structure were found to increase in an additive fashion its binding to the antibodies and renal cell receptors. The relative binding activity of the analogues carrying a double modification can be assessed if the activities of the analogues with the appropriate single modifications are known. It was concluded that the testing of modifications in the peptide structure for their additivity may provide some insight into the conformational properties of peptides during their binding to the protein.
Asunto(s)
Corteza Suprarrenal/metabolismo , Angiotensina II/metabolismo , Anticuerpos/metabolismo , Receptores de Angiotensina/metabolismo , Receptores de Superficie Celular/metabolismo , Angiotensina II/análogos & derivados , Animales , Sitios de Unión de Anticuerpos , Técnicas In Vitro , Cinética , Modelos Biológicos , Conformación Proteica , Conejos/inmunología , Radioinmunoensayo , Ensayo de Unión Radioligante , RatasRESUMEN
The interaction of angiotensin analogs modified at position 8 with specific antibodies has been studied. Modification of phenylalanine in the angiotensin molecule results in a decrease or disappearance of activity of the compounds tested. This allowed to develop a selective approach for determination of angiotensin antagonists in the blood.
Asunto(s)
Angiotensinas/sangre , Anticuerpos , Complejo Antígeno-Anticuerpo , Humanos , Inmunoensayo , Relación Estructura-ActividadRESUMEN
The antigen activity of angiotensin, its fragments and analogues, which contain enantiomeric forms of amino acids and aza-alpha'-homoamino acids is studied by cross reactions with specific antibodies, obtained for angiotensin and its central tetrapeptide. It is found that the inclusion of additional NH-group between alpha carbon and carboxyl group of peptide chain, although in few cases radically changes spatial structure of compounds, does not deprivate their antigen activity. The replacement of NH-group to the C-end of the angiotensin molecule by affection the antigen determinant considerably decreases the antigen activity of the analogues. The important role in the determination of the antigen activity play the tyrosine residue and its specific orientation with respect to the antigen molecule. Low molecular weight fragments and analogues of the central part of angiotensin molecule, which have less "rigid" spatial structures, are capable to reorganize their spatial structure during interaction with antibodies.
Asunto(s)
Angiotensina II/inmunología , Aminoácidos , Reacciones Cruzadas , Epítopos , Fragmentos de Péptidos , Conformación Proteica , EstereoisomerismoRESUMEN
The antigenic activity of angiotensin and its seven fragments has been studied in cross-reaction with specific antibodies, elicited to angiotensin and its fragments: C-terminal hexapeptide and middle tetrapeptide. It has been found that all the fragments studied possess certain affinity for antibodies elicited to angiotensin, C-terminal hexapeptide and middle tetrapeptide. The middle tetrapeptide was identified to be the immunologically active centre of the angiotensin molecule.