בבקשה (באנגלית - בקיצור)
For over three decades, bacteriorhodopsin has served as a paradigm for the study of the mechanisms underlying ion pumping across biological membranes. It is perhaps among the simplest known ion pumps, which functions by converting light energy into an electrochemical gradient by pumping protons out of the cytoplasm. The combination of spectroscopic, biochemical and crystallographic studies on bacteriorhodopsin provides a unique opportunity to dissect the principal elements underlying the mechanism of transmembrane proton transport. Here, we provide a brief review of recent developments related to the determination of the structural changes during proton transport using crystallographic approaches. Taken together with previous spectroscopic and biochemical investigations, these studies allow the description of a detailed molecular mechanism of the main steps in vectorial proton transport by bacteriorhodopsin. ובהקשר קצת יותר מעניין: Bacteriorhodopsin (BR) is the photoactive proton pump found in the purple membrane of the salt marsh archaeon Halobacterium salinarum. Evolution has optimized this protein for high photochemical efficiency, thermal stability and cyclicity, as the organism must be able to function in a hot, stagnant and resource-limited environment. Photonic materials generated via organic chemistry have yet to surpass the native protein in terms of quantum efficiency or cyclicity. However, the native protein still lacks the overall efficiency necessary for commercial viability and virtually all successful photonic devices using bacteriorhodopsin are based on chemical or genetic variants of the native protein. We show that genetic engineering can provide significant improvement in the device capabilities of proteins and, in the case of bacteriorhodopsin, a 700-fold improvement has been realized in volumetric data storage. We conclude that semi-random mutagenesis and directed evolution will play a prominent role in future efforts in bioelectronic optimization.
