RESUMO
In this review we have focused on the advances madein observing the photo-induced response in bacteriorhodopsin and understanding the mechanisms of retinal-protein interactions which are still obscure. We discuss our recent data obtained on the wild type of bacteriorhodopsin and model compounds. This paper presents our new spectroscopic data on amino acids obtained using FT-IR emission spectroscopy. Based on the characteristics of the structure and optical properties of glycine and L-lysine that simulate a photo-induced behaviour of an opsin under natural conditions we tried to find an answer to one of the most important questions concerning the role of protein in the primary processes in bacteriorhodopsin.
Assuntos
Bacteriorodopsinas/química , Glicina/química , Lisina/química , Opsinas/química , Cinética , Luz , Opsinas/metabolismo , Ligação Proteica , Retinaldeído/química , Espectroscopia de Infravermelho com Transformada de FourierRESUMO
Tetradecapeptides (RLARLAR)2, D-(RLARLAR)2, (RLARLAA)2, and (RLGRLGR)2 were synthesized by a solid phase method using Fmoc-amino acids. The antibacterial activity of the synthesized peptides was studied against Escherichia coli cells. The minimum inhibitory concentration (MIC) was, correspondingly, 3, 1, 3, and 12 micro M, which is comparable with MIC of such natural antimicrobial peptides as temporin, magainin, and dermaseptin. It was found that all of the synthesized peptides have no effect on human erythrocytes and rat thymocytes. The peptides form alpha-helices in 30% trifluoroethanol and in 2.5 mM SDS, which have amphipathic structure.
Assuntos
Antibacterianos/química , Anti-Infecciosos/farmacologia , Arginina/química , Peptídeos/química , Sequência de Aminoácidos , Proteínas de Anfíbios/farmacologia , Animais , Peptídeos Catiônicos Antimicrobianos/farmacologia , Arginina/farmacologia , Eritrócitos/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Escherichia coli/ultraestrutura , Humanos , Microscopia Eletrônica , Dados de Sequência Molecular , Peptídeos/farmacologia , Proteínas/farmacologia , Ratos , Linfócitos T/efeitos dos fármacosRESUMO
Vibrational IR-emission spectra of bacteriorhodopsin (bR) were recorded under continuous illumination with visible light at room temperature. They contain selective information about the chromophore, Schiff base, and opsin. The spectral bands were identified by comparing the data with resonance Raman and IR absorption data. The IR-emission spectra were shown to contain a set of bands characteristic for both all-trans (bR568) and 13-cis conformations (K610-like intermediate) simultaneously. Variation of spectral composition and the intensity of visible light illumination influenced the spectral traces and intensity distribution between them. Greater intensity of deformational vibrations suggests distorted retinal structure in the vibrationally excited ground electronic state. The origin of the emitting species of bR is discussed.
