![]() FIG.1 1 shows the structure of the KcsA channel and its selectivity filter. Ion channels allow ions to enter or leave cells in a very selective and rapid manner. The selectivity filter is capable of selecting potassium ions over sodium ions in a ratio of 10 4 : 1. The process of gating, i.e., the mechanism that controls the closing and opening of the pores, is different in the variety of potassium channels, but the sequence of amino acids forming the selection filter is the same in all potassium channels 15. The ions must move in a single file without their hydration shell in this filter. The selectivity filter width is only a few angstroms (3A). Each P-loop is composed of five amino acids: linked by peptide units (H–N–C=O). The 3.4 nm long KcsA channel is comprised of a 1.2 nm long selectivity filter that is composed of four P-loop monomers. The structure of this filter is well studied in the Streptomyces lividans (KcsA) bacterial channel 15. Another common feature is having a selectivity filter responsible for passing only one specific type of ion. Ion channels share common properties, the most important of which is the presence of a gate that can be activated by such factors as chemicals, voltage, light, and mechanical pressure. Structurally, ion channels are protein complexes comprised of several subunits whose cyclic arrangement forms sub-nanometer pores for ions to enter or leave the cell 1. These channels are a collection of proteins embedded in the cell membrane that tune the flux of specific ions across the membrane and regulate interactions between the cell and its environment 14. Due to the energy scale and transport phenomena, ion channels can be considered as a distinct protein system that the quantum effects may have a functional role within them so that their activities can be comprehended via quantum mechanics 11. Recently, it has been proposed that quantum coherence may play a role in the selectivity of ions and their transport through ion channels 11– 13. According to this evidence, the role of quantum phenomena, such as tunneling and quantum coherence, has been widely accepted in the crucial activities of living cells 10. The newfound evidence, in recent years, reveals that quantum principles play a critical role in explaining various biological phenomena such as photosynthesis, quantum effects in the brain, and spin and electromagnetic routing of the migratory birds 4– 9. In the beginning, it was believed that quantum phenomena such as tunneling or quantum entanglement do not exist in living environments since these environments are inherently warm, humid, and noisy 1– 3. ![]() Quantum biology is a relatively new field of study in quantum mechanics which can use quantum theory in some aspects of biology that classical physics cannot describe precisely. The oscillation of distillable coherence from zero, after the decoherence time, and also the behavior of the coherence function clearly show the point that the system is coherent in ion channels with high throughput rates. We studied the distillable coherence and the second order coherence function of the system. Using the Lindblad equation to describe a three-level system, the results in different quantum regimes are examined. ![]() The present research is an attempt to investigate the relationship between hopping rate and maintaining coherence in ion channels. To do this, ion channels must be highly selective, allowing only certain ions to pass through the membrane, while preventing the others. One of their main physiological functions is the efficient and highly selective transfer of K + ions through the membranes into the cells. Potassium channels play a vital role in many physiological processes. ![]() Recently, it has been suggested that ion channel selectivity filter may exhibit quantum coherence, which may be appropriate to explain ion selection and conduction processes. ![]()
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