RESUMO
OB protein (or leptin) administration causes a long-lasting reduction in food intake and body weight in obese ob/ob mice. Neuropeptide Y, a stimulator of feeding, has been proposed to be a major mediator of the biological actions of OB protein. To test this hypothesis, the interaction of brain administration of exogenous OB protein and NPY on the feeding behavior of ob/ob mice was examined. Human OB protein, in a dose-dependent manner, partially or completely blocked feeding induced by exogenous NPY. These results demonstrate that OB protein can functionally antagonize and dominate the actions of exogenous NPY on feeding.
Assuntos
Encéfalo/efeitos dos fármacos , Ingestão de Alimentos/efeitos dos fármacos , Neuropeptídeo Y/administração & dosagem , Proteínas/administração & dosagem , Animais , Encéfalo/fisiologia , Hormônio Liberador da Corticotropina/fisiologia , Interações Medicamentosas , Ingestão de Alimentos/fisiologia , Feminino , Humanos , Injeções Intraventriculares , Leptina , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Obesos , Neuropeptídeo Y/fisiologia , Obesidade/etiologia , Obesidade/fisiopatologia , Pró-Opiomelanocortina/fisiologia , Proteínas/fisiologia , Proteínas Recombinantes/administração & dosagemAssuntos
Comportamento Alimentar/fisiologia , Neuropeptídeo Y/fisiologia , Animais , Implantes de Medicamento , Humanos , Leptina , Camundongos , Camundongos Endogâmicos C57BL , Neuropeptídeo Y/administração & dosagem , Neuropeptídeo Y/antagonistas & inibidores , Obesidade , Proteínas/administração & dosagem , Proteínas/fisiologiaRESUMO
Conformation of highly purified recombinant human fibroblast interferon-beta (rHuIFN-beta) was correlated with its biological activity. The extent of ordered secondary structure was determined by circular dichroic (CD) spectroscopy in various buffer conditions to establish conditions of protein stability and its potential for helix formation. The highest "helicity" (about 50 +/- 5% of alpha-helices) and the highest antiviral activities (4-10 x 10(7) units/mg) were found in 50% ethylene glycol, 1 M NaCl and 0.05 M Na3PO4, pH 7.2 (Buffer I); 80 mM citric acid, 20 mM Na2HPO4, pH 2.9 (Buffer II); and 25 mM NH4OAc, 125 mM NaCl, pH 5.1 (Buffer III). Both helicity and antiviral activity of the IFN-beta decrease in parallel with denaturation by urea, heat, and/or by repeated cycles of freezing and thawing. Low pH (pH 2.9 Buffer II) exhibits a distinct stabilizing effect on the structure and antiviral activity of IFN-beta against heat denaturation.
Assuntos
Interferon Tipo I , Sequência de Aminoácidos , Soluções Tampão , Dicroísmo Circular , Eletroforese em Gel de Poliacrilamida , Humanos , Interferon Tipo I/análise , Interferon Tipo I/farmacologia , Dados de Sequência Molecular , Conformação Proteica , Desnaturação Proteica , Proteínas Recombinantes , Relação Estrutura-AtividadeRESUMO
There is good agreement between the target molecular weight and the known molecular weight of human leukocyte interferons (about 20,000). The target molecular weight of fibroblast interferon, 31,000 to 42,000, is significantly larger than the monomer molecular weight of 21,000 to 24,000, suggesting that the dimer may be the predominant active functional unit in solution. A range from 63,000 to 73,000 for the target molecular weight of several different fractions of immune interferon (including natural crude as well as the recombinant form) indicates that the functional form of the immune interferon may be a trimer or tetramer. Thus, these studies indicate that the functional unit of leukocyte interferon is the monomer, that of fibroblast interferon is a dimer, and that of immune interferon is probably a tetramer (or trimer).
