Secondary structures comparison of aquaporin-1 and bacteriorhodopsin: a Fourier transform infrared spectroscopy study of two-dimensional membrane crystals

摘要: Aquaporins are integral membrane proteins found in diverse animal and plant tissues that mediate the permeability of plasma membranes to water molecules. Projection maps two-dimensional crystals aquaporin-1 (AQP1) reconstituted lipid suggested presence six eight transmembrane helices protein. However, data from other sequence spectroscopic analyses indicate this protein may adopt a porin-like beta-barrel fold. In paper, we use Fourier transform infrared spectroscopy characterize secondary structure highly purified native proteolyzed AQP1 crystalline arrays compare it bacteriorhodopsin. For analysis fractional contents have been determined by using several different algorithms. addition, neural network-based evaluation spectra terms numbers segments their interconnections [sij] has performed. The following conclusions were reached: 1) is helical (42-48% alpha-helix) with little or no beta-sheet content. 2) alpha-helices orientation, but more tilted (21 degrees 27 degrees, depending on considered refractive index) than bacteriorhodopsin helices. 3) undergo limited hydrogen/deuterium exchange thus not readily accessible solvent. Our support structural model derived prediction epitope insertion experiments: at least closely associated span membrane.