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Bacterial Leucine Transporter
Bacterial Leucine Transporter (LeuT) is a bundled twelve alpha helix protein which belongs to the family of transporters that shuttle amino acids in and out of bacterial cells. Specialized in small hydrophobic amino acids such as leucine and alanine, this transporter is powered by the gradient of sodium ions that is normally maintained by healthy cells across their membranes. LeuT acts as a symporter, which means that it links the passage of a sodium ion across the cell membrane with the transport of the amino acid in the same direction. It was first crystallized to understand the inner molecular mechanisms of antidepressant's work since it has a close resemblance with the human neurotransmitter transporters (more difficult to crystallize) that these drugs block, thus inhibiting the reuptake of chemical messengers across the cell membrane of nerve axons and glial cells. Structure LeuT is a homodimer composed by two identical Protein subunit, subunits which are in contact in two ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alpha Helix
The alpha helix (α-helix) is a common motif in the secondary structure of proteins and is a right hand-helix conformation in which every backbone N−H group hydrogen bonds to the backbone C=O group of the amino acid located four residues earlier along the protein sequence. The alpha helix is also called a classic Pauling–Corey–Branson α-helix. The name 3.613-helix is also used for this type of helix, denoting the average number of residues per helical turn, with 13 atoms being involved in the ring formed by the hydrogen bond. Among types of local structure in proteins, the α-helix is the most extreme and the most predictable from sequence, as well as the most prevalent. Discovery In the early 1930s, William Astbury showed that there were drastic changes in the X-ray fiber diffraction of moist wool or hair fibers upon significant stretching. The data suggested that the unstretched fibers had a coiled molecular structure with a characteristic repeat of ≈. Astb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
