RESUMO
Melittin induces various reactions in membranes and has been widely studied as a model for membrane-interacting peptide; however, the mechanism whereby melittin elicits its effects remains unclear. Here, we observed melittin-induced changes in individual giant liposomes using direct real-time imaging by dark-field optical microscopy, and the mechanisms involved were correlated with results obtained using circular dichroism, cosedimentation, fluorescence quenching of tryptophan residues, and electron microscopy. Depending on the concentration of negatively charged phospholipids in the membrane and the molecular ratio between lipid and melittin, melittin induced the "increasing membrane area", "phased shrinkage", or "solubilization" of liposomes. In phased shrinkage, liposomes formed small particles on their surface and rapidly decreased in size. Under conditions in which the increasing membrane area, phased shrinkage, or solubilization were mainly observed, the secondary structure of melittin was primarily estimated as an α-helix, ß-like, or disordered structure, respectively. When the increasing membrane area or phased shrinkage occurred, almost all melittin was bound to the membranes and reached more hydrophobic regions of the membranes than when solubilization occurred. These results indicate that the various effects of melittin result from its ability to adopt various structures and membrane-binding states depending on the conditions.
Assuntos
Proteínas de Insetos/química , Bicamadas Lipídicas/química , Meliteno/química , Proteínas de Membrana/química , Fosfolipídeos/química , Animais , Fenômenos Químicos , Dicroísmo Circular , Interações Hidrofóbicas e Hidrofílicas , Proteínas de Insetos/metabolismo , Cinética , Bicamadas Lipídicas/metabolismo , Lipossomos , Meliteno/metabolismo , Proteínas de Membrana/metabolismo , Membranas/química , Membranas/metabolismo , Membranas/ultraestrutura , Microscopia Eletrônica de Transmissão , Fosfatidilcolinas/química , Fosfatidilcolinas/metabolismo , Fosfatidilgliceróis/química , Fosfatidilgliceróis/metabolismo , Fosfolipídeos/metabolismo , Estrutura Secundária de Proteína , Solubilidade , Propriedades de Superfície , Triptofano/químicaRESUMO
As a method of reducing lifestyle-related diseases and guidance in small- and medium-sized enterprises where blood examination by blood collection from the upper arm cannot be performed, we developed a program for reducing lifestyle-related diseases by blood analysis using a fingertip collection kit and a small centrifuge, and evaluated this program in small- and medium-sized enterprises. During a 6-month period, a total of 7 interviews and a total of 3 own blood collections were performed by workers showing abnormalities in items associated with lifestyle-related diseases, such as lipids and glucose, in a periodic medical examination. Many of the participants in this program showed improvement in blood analysis data (triglyceride), abdominal circumference, and body weight. The cost of the examination was low. This self-monitoring method, which is based on objective data and can be readily and easily performed in the workplace, may be useful for reducing lifestyle-related diseases.
Assuntos
Análise Química do Sangue/métodos , Coleta de Amostras Sanguíneas/métodos , Intolerância à Glucose/prevenção & controle , Hiperlipidemias/prevenção & controle , Monitorização Fisiológica , Obesidade/prevenção & controle , Saúde Ocupacional , Adulto , Automonitorização da Glicemia , Feminino , Humanos , Estilo de Vida , Masculino , Pessoa de Meia-Idade , AutocuidadoRESUMO
We examined the effects on whole blood viscosity and coagulation time of various dosages of the synthetic low-molecular protease inhibitors gabexate mesilate and nafamostat mesilate with an oscillation-type viscometer. When either agent was added, blood viscosity decreased dose-dependently along a sigmoid-like curve. Furthermore, coagulation time was shorter with gabexate mesilate than with nafamostat mesilate owing to the differences of half-life in human blood. Thrombin generation, which results from the activation of coagulation factors, is inhibited by synthetic protease inhibitors and subsequently decreases blood viscosity dose-dependently.