Search results
Results From The WOW.Com Content Network
A dihedral angle is the angle between two intersecting planes or half-planes. ... This is the case for kinematic chains or amino acids in a protein structure. In ...
One is to show in theory which values, or conformations, of the ψ and φ angles are possible for an amino-acid residue in a protein (as at top right). A second is to show the empirical distribution of datapoints observed in a single structure (as at right, here) in usage for structure validation , or else in a database of many structures (as ...
Thus, the γ-turn has two forms, a classical form with (φ, ψ) dihedral angles of roughly (75°, −65°) and an inverse form with dihedral angles (−75°, 65°). At least eight forms of the beta turn occur, varying in whether a cis isomer of a peptide bond is involved and on the dihedral angles of the central two residues.
Because not all amino acids have these dihedral angles, a Janin plot is not applicable to all such acids. This correlation is different for the various amino acids and can depend on the type of secondary structure (Helix, Sheet, etc.) local to that residue. The plot is named for Joël Janin, who studied these correlations in 1978 with Shoshana ...
The first approach uses discrete variables for representing the coordinates or the dihedral angles of the protein structure. The variables are originally all continuous values and, to transform them into discrete values, a discretization process is typically applied. The second approach uses continuous variables for the coordinates or dihedral ...
Some proteins that are disordered or helical as monomers, such as amyloid β (see amyloid plaque) can form β-sheet-rich oligomeric structures associated with pathological states. The amyloid β protein's oligomeric form is implicated as a cause of Alzheimer's. Its structure has yet to be determined in full, but recent data suggest that it may ...
The majority of π-helices are only 7 residues in length and do adopt regularly repeating (φ, ψ) dihedral angles throughout the entire structure like that of α-helices or β-sheets. Because of this, textbooks that provide single dihedral values for all residues in the π-helix are misleading. Some generalizations can be made, however.
A polyproline helix is a type of protein secondary structure which occurs in proteins comprising repeating proline residues. [1] A left-handed polyproline II helix (PPII, poly-Pro II, κ-helix [2]) is formed when sequential residues all adopt (φ,ψ) backbone dihedral angles of roughly (-75°, 150°) and have trans isomers of their peptide bonds.