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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.
Multiple prolines and/or hydroxyprolines in a row can create a polyproline helix, the predominant secondary structure in collagen. The hydroxylation of proline by prolyl hydroxylase (or other additions of electron-withdrawing substituents such as fluorine ) increases the conformational stability of collagen significantly. [ 20 ]
These methods were based on the helix- or sheet-forming propensities of individual amino acids, sometimes coupled with rules for estimating the free energy of forming secondary structure elements. The first widely used techniques to predict protein secondary structure from the amino acid sequence were the Chou–Fasman method [ 17 ] [ 18 ] [ 19 ...
Bahasa Indonesia; Italiano; ... Polyproline I helix; Protein–protein interaction; Medicine ... Perusahaan Perdagangan Indonesia, trading company;
In addition to the protein domains, there are unusual transmembrane elements formed by peptides. A typical example is gramicidin A, a peptide that forms a dimeric transmembrane β-helix. [8] This peptide is secreted by gram-positive bacteria as an antibiotic. A transmembrane polyproline-II helix has not been reported in natural proteins ...
Polyproline helix; S. Superhelix; T. Tendril perversion; TMPad; Triple helix; X. Xeno nucleic acid This page was last edited on 1 March 2024, at 23:14 (UTC). Text is ...
In such rings the polypeptide has the conformation of beta sheet or of type II polyproline helix (PPII). A number of glutamines and asparagines help bind short peptides (with the PPII conformation) in the groove of class II MHC ( Major Histocompatibility Complex ) proteins [ 2 ] by forming these motifs.
Bahasa Indonesia; עברית ... They are very short genes containing the characteristic collagen-triple helix sequence, as well as polyproline domains and cysteine ...