Supersecondary structure
Encyclopedia
A supersecondary structure is a compact three-dimensional protein structure
of several adjacent elements of secondary structure
that is smaller than a protein domain
or a subunit
. Supersecondary structures can act as nucleation
s in the process of protein folding
. Examples include β-hairpins
, α-helix hairpins, and β-α-β motifs.
Protein structure
Proteins are an important class of biological macromolecules present in all organisms. Proteins are polymers of amino acids. Classified by their physical size, proteins are nanoparticles . Each protein polymer – also known as a polypeptide – consists of a sequence formed from 20 possible L-α-amino...
of several adjacent elements of secondary structure
Secondary structure
In biochemistry and structural biology, secondary structure is the general three-dimensional form of local segments of biopolymers such as proteins and nucleic acids...
that is smaller than a protein domain
Protein domain
A protein domain is a part of protein sequence and structure that can evolve, function, and exist independently of the rest of the protein chain. Each domain forms a compact three-dimensional structure and often can be independently stable and folded. Many proteins consist of several structural...
or a subunit
Protein subunit
In structural biology, a protein subunit or subunit protein is a single protein molecule that assembles with other protein molecules to form a protein complex: a multimeric or oligomeric protein. Many naturally occurring proteins and enzymes are multimeric...
. Supersecondary structures can act as nucleation
Nucleation
Nucleation is the extremely localized budding of a distinct thermodynamic phase. Some examples of phases that may form by way of nucleation in liquids are gaseous bubbles, crystals or glassy regions. Creation of liquid droplets in saturated vapor is also characterized by nucleation...
s in the process of protein folding
Protein folding
Protein folding is the process by which a protein structure assumes its functional shape or conformation. It is the physical process by which a polypeptide folds into its characteristic and functional three-dimensional structure from random coil....
. Examples include β-hairpins
Beta hairpin
The beta hairpin structural motif is the simplest protein motif involving two beta strands that look like a hairpin. The motif consists of two strands that are adjacent in primary structure oriented in an antiparallel arrangement and linked by a short loop of two to five amino acids...
, α-helix hairpins, and β-α-β motifs.