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Beta sheets consist of beta strands (β-strands) connected laterally by at least two or three backbone hydrogen bonds, forming a generally twisted, pleated sheet. A β-strand is a stretch of polypeptide chain typically 3 to 10 amino acids long with backbone in an extended conformation .
Antiparallel and parallel beta sheet. Many proteins may adopt a beta sheet as part of their secondary structure. In beta sheets, sections of a single polypeptide may run side-by-side and antiparallel to each other, to allow for hydrogen bonding between their backbone chains. Beta sheets can also be either a parallel or anti-parallel secondary ...
Secondary structure elements in HB plot, there is swapped parallel and anti-parallel sheets. In representations of the HB plot, characteristic patterns of secondary structure elements can be recognised easily, as follows: Helices can be identified as strips directly adjacent to the diagonal. Antiparallel beta sheets appear in HB plot as cross ...
E = extended strand in parallel and/or anti-parallel β-sheet conformation. Min length 2 residues. B = residue in isolated β-bridge (single pair β-sheet hydrogen bond formation) S = bend (the only non-hydrogen-bond based assignment). C = coil (residues which are not in any of the above conformations).
A beta hairpin is a common supersecondary motif composed of two anti-parallel beta strands connected by a loop. The structure resembles a hairpin and is often found in globular proteins. The loop between the beta strands can range anywhere from 2 to 16 residues. However, most loops contain less than seven residues. [2]
The Cα-atoms alternate above and below the sheet in a pleated structure, and the R side groups of the amino acids alternate above and below the pleats. The Φ and Ψ angles of the amino acids in sheets vary considerably in one region of the Ramachandran plot. It is more difficult to predict the location of β-sheets than of α-helices.
The other type is the G1 beta bulge, of which there are two common sorts, both mainly occurring in association with antiparallel sheet; one residue has the α L conformation and is usually a glycine. In one sort, the beta bulge loop , one of the hydrogen bonds of the beta-bulge also forms a beta turn or alpha turn, such that the motif is often ...
The winged helix-turn-helix (wHTH) motif is formed by a 3-helical bundle and a 3- or 4-strand beta-sheet (wing). The topology of helices and strands in the wHTH motifs may vary. In the transcription factor ETS wHTH folds into a helix-turn-helix motif on a four-stranded anti-parallel beta-sheet scaffold arranged in the order α1-β1-β2-α2-α3 ...