The structure of collagen
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The Structure of Collagen
Triple Helical Structure of Collagen
Collagen is the most abundant protein in animals, characterized by its unique triple helical structure. This structure consists of three parallel, left-handed polyproline II-type helices that form a right-handed bundle1. The triple helix is stabilized by hydrogen bonds, with two hydrogen bonds for every three residues, although some models suggest one hydrogen bond per three residues to avoid interatomic clashes3. The helices are non-coaxial and linked by hydrogen bonds approximately perpendicular to the chain length4.
Molecular and Microfibrillar Arrangement
The molecular structure of collagen has been extensively studied using X-ray diffraction, revealing detailed coordinates and Fourier transforms that match observed data2. The collagen molecules are arranged in a supertwisted, right-handed microfibril structure that interdigitates with neighboring microfibrils, forming a quasihexagonal packing topology5. This arrangement is crucial for the mechanical properties and biological functions of collagen in tissues.
Hierarchical Structure and Stability
Collagen exhibits a multi-hierarchical fibrous architecture, which is essential for its bioactivity and mechanical properties8. The stability of the collagen triple helix is influenced by stereoelectronic effects and preorganization, which are critical for maintaining its structural integrity1. The hierarchical structure includes various levels of organization, from the triple helix to fibrils and larger supramolecular aggregates9.
Types and Functions of Collagen
There are 14 types of collagen, each with distinct structural and functional roles. Fibrillar collagens (types I, II, III, V, and XI) form the primary structural components of connective tissues, while other types, such as type IV, form sheet-like structures in basement membranes6. Collagen types also include fibril-associated collagens with interrupted triple helices (FACITs) and anchoring fibrils that connect different tissue components6.
Mechanical Properties and Biomedical Applications
Collagen's mechanical properties, such as strength and extensibility, make it suitable for various biological functions, including in tendons, bones, and skin7. However, collagen's poor physical and chemical properties necessitate modifications for biomedical applications. Crosslinking methods have been developed to enhance collagen's mechanical strength, thermostability, and resistance to enzymatic degradation, making it a valuable material for skin substitutes, bone and tendon repair, and other medical uses8.
Conclusion
The structure of collagen is a complex and highly organized system that plays a crucial role in the mechanical and biological functions of connective tissues. Its triple helical structure, hierarchical organization, and various types contribute to its stability and functionality. Understanding these structural details is essential for developing advanced collagen-based biomaterials for biomedical applications.
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Most relevant research papers on this topic
Collagen structure and stability.
Understanding collagen structure and stability, along with stereoelectronic effects and preorganization, will guide the development of artificial collagenous materials for biomedicine and nanotechnology.
Highly CitedThe molecular structure of collagen.
This paper demonstrates that only two basic types of collagen structures are possible, and compares the predicted coordinates and Fourier transforms with observed X-ray diffraction data.
Highly CitedStructure of Collagen
The triple helical structure of collagen can be constructed with two hydrogen bonds for every three residues, retaining all permissible interatomic contacts and maintaining the observed frequency of 3.0.
Highly CitedStructure of Collagen
The structure of collagen is a three-chain coiled-coil, similar to the one found in elastin, with minor modifications.
Microfibrillar structure of type I collagen in situ.
The crystallographic determination of collagen type I's supermolecular structure reveals its molecular packing topology, providing insights into biological processes and diseases like heart disease and cancer.
Highly CitedCollagen family of proteins
Fourteen collagen types form diverse structures in connective tissues, basement membranes, and worm cuticle, playing a crucial role in tissue connectivity.
Highly CitedThe structure of fibrous proteins of the collagen-gelatin group.
This study proposes a new, precise configuration for collagen and gelatin, which explains the positions and intensities of x-ray diffraction maxima.
Highly CitedRecent advances of collagen-based biomaterials: Multi-hierarchical structure, modification and biomedical applications.
Collagen-based biomaterials show promise for biomedical applications, but require modification for improved mechanical strength, thermostability, and resistance to enzymes.
Highly CitedCollagen Structural Hierarchy and Susceptibility to Degradation by Ultraviolet Radiation.
The native collagen triple helix is most sensitive to UV-254nm radiation, affecting tissue remodeling, wound repair, and disease progression.
In Vitro StudyHighly Cited