An alpha helix (or α-helix) is a sequence of amino acids in a protein that are twisted into a coil (a helix). The alpha helix is the most common structural arrangement in the secondary structure of proteins. It is also the most extreme type of local structure, and it is the local structure that is most easily predicted from a sequence of amino acids. The alpha helix has a right hand-helix conformation in which every backbone N−H group hydrogen bonds to the backbone C=O group of the amino acid that is four residues earlier in the protein sequence.
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 ≈5.1 ångströms (0.51 nanometres). Astbury initially proposed a linked-chain structure for the fibers. Although incorrect in their details, Astbury's models of these forms were correct in essence and correspond to modern elements of secondary structure, the α-helix and the β-strand (Astbury's nomenclature was kept), which were developed by Linus Pauling, Robert Corey and Herman Branson in 1951, that paper showed both right- and left-handed helices, although in 1960 the crystal structure of myoglobin, showed that the right-handed form is the common one. Here you can see an helical bundle as appeared in the cryoEM structure of human GPR156 receptor (PDB code: 8IEP)
#molecularart ... #helix ..: #bundle ... #alpha ... #cryoem
Structure rendered with @proteinimaging and post-processed with @stylar.ai_official
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 ≈5.1 ångströms (0.51 nanometres). Astbury initially proposed a linked-chain structure for the fibers. Although incorrect in their details, Astbury's models of these forms were correct in essence and correspond to modern elements of secondary structure, the α-helix and the β-strand (Astbury's nomenclature was kept), which were developed by Linus Pauling, Robert Corey and Herman Branson in 1951, that paper showed both right- and left-handed helices, although in 1960 the crystal structure of myoglobin, showed that the right-handed form is the common one. Here you can see an helical bundle as appeared in the cryoEM structure of human GPR156 receptor (PDB code: 8IEP)
#molecularart ... #helix ..: #bundle ... #alpha ... #cryoem
Structure rendered with @proteinimaging and post-processed with @stylar.ai_official
