What is a triple helix protein?
The triple helix is an important motif found in the family of collagens as well as a set of host-defense proteins. This conformation may be identified by its strict sequence constraints, including glycine as every third residue and a high content of imino acids.
What is a triple helical DNA?
Triple-stranded DNA (also known as H-DNA or Triplex-DNA) is a DNA structure in which three oligonucleotides wind around each other and form a triple helix.
Is triple helix a secondary structure?
The triple-helix is a unique secondary structural motif found primarily within the collagens. In collagen, it is a homo- or hetero-tripeptide with a repeating primary sequence of (Gly-X-Y)n, displaying characteristic peptide backbone dihedral angles.
What is the function of triple helix structure in collagen?
The collagen triple helix has been considered as a proto- type of a rod-like protein whose role is self-association to form fibrils, but there is an increasing appreciation of its role in specific binding of other molecules (Table I).
How does a triple helix form?
A triple helix is formed after the binding of a third strand to the major groove of a duplex DNA through Hoogsteen base pairing. Pyrimidine-rich and purine-rich sequences can form stable triplex structures as a consequence of the formation of A–T–A and C+–G–C triplets (Fig. (B) An antiparallel triplex structure.
Is a triple helix a quaternary structure?
Collagens have a triple helix as the major structure. The quaternary structure of collagen consists of three left-handed helices twisted into a right-handed coil.
What causes triplex DNA structures?
A DNA triplex is formed when pyrimidine or purine bases occupy the major groove of the DNA double Helix forming Hoogsteen pairs with purines of the Watson-Crick basepairs.
Is a triple helix a tertiary structure?
All multicellular animals possess collagens as major structural proteins which are responsible for maintaining the structural integrity of tissues and organs. Collagens are characterized by their unique tertiary structure, called the collagen triple helix, and by their existence in extracellular matrices (ECMs).
What is triple helical structure of collagen?
The triple-helical structure of collagen arises from an unusual abundance of three amino acids: glycine, proline, and hydroxyproline. Hydrogen bonds linking the peptide bond NH of a glycine residue with a peptide carbonyl (C═O) group in an adjacent polypeptide help hold the three chains together.
What bonds stabilize collagen triple helix?
Collagen mimics are peptides designed to reproduce structural features of natural collagen. A triple helix is the first element in the hierarchy of collagen folding. It is an assembly of three parallel peptide chains stabilized by packing and interchain hydrogen bonds.
What causes triplex DNA structure?
Who first proposes a triple helical model for the structure of collagen?
This year marks the 50th anniversary of the coiled-coil triple helical structure of collagen, first proposed by Ramachandran’s group from Madras. The original structure was postulated to be stabilized by two interchain hydrogen bonds, per tripeptide.
What kind of structure is a triple helix?
Each assembly is characterized by a hallmark feature, a protein structure called a triple helix. A current gap in knowledge is understanding the mechanisms of how the triple helix encodes and utilizes information in building scaffolds on the outside of cells.
Where does the triple helix of collagens come from?
A hallmark feature of all collagens is the triple helix, which is characterized by three intertwined polypeptide chains. A collagen IV-like gene probably first appeared in the last common ancestor (LCA) to filastereans, choanoflagellates and animals.
Can a minichain form a triple helical homotrimer?
A minichain consisting of COL1 and the N-terminal portion of the NC1 domain has been successfully self-assembled into a triple helical homotrimer stabilized by the cystine knot. 469 The most interesting and practically important way would be to form a heterotrimeric FACIT cystine knot found in type IX collagen.
How are glycines shown in the triple helix?
Gly position residues (including the mutated glycines) are shown in darkest color, X-positions in the middle-gray and Y-positions in the lightest gray color. The circle illustrates the normal diameter of the triple helix. Larger distortions and helix expansion are visible with bulkier residue replacing Gly.