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Protein secondary structure is the local spatial conformation of the polypeptide backbone excluding the side chains. [1] The two most common secondary structural elements are alpha helices and beta sheets, though beta turns and omega loops occur as well. Secondary structure elements typically spontaneously form as an intermediate before the ...
An alpha helix (or α-helix) is a sequence of amino acids in a protein that are twisted into a coil (a helix). The alpha helix is the most common structural arrangement in the secondary structure of proteins. It is also the most extreme type of local structure, and it is the local structure that is most easily predicted from a sequence of amino ...
Protein folding. Protein folding is the physical process by which a protein, after synthesis by a ribosome as a linear chain of amino acids, changes from an unstable random coil into a more ordered three-dimensional structure. This structure permits the protein to become biologically functional.
A transmembrane protein is a type of integral membrane protein that spans the entirety of the cell membrane. Many transmembrane proteins function as gateways to permit the transport of specific substances across the membrane. They frequently undergo significant conformational changes to move a substance through the membrane.
An alpha-helix with hydrogen bonds (yellow dots) The α-helix is the most abundant type of secondary structure in proteins. The α-helix has 3.6 amino acids per turn with an H-bond formed between every fourth residue; the average length is 10 amino acids (3 turns) or 10 Å but varies from 5 to 40 (1.5 to 11 turns). The alignment of the H-bonds ...
A coiled coil is a structural motif in proteins in which 2–7 [1] alpha-helices are coiled together like the strands of a rope. (Dimers and trimers are the most common types.) They have been found in roughly 5-10% of proteins and have a variety of functions. [2] They are one of the most widespread motifs found in protein-protein interactions.
In molecular biology, a protein domain is a region of a protein 's polypeptide chain that is self-stabilizing and that folds independently from the rest. Each domain forms a compact folded three-dimensional structure. Many proteins consist of several domains, and a domain may appear in a variety of different proteins.
This 'globin fold' typically consists of eight alpha helices, although some proteins have additional helix extensions at their termini. [4] Since the globin fold contains only helices, it is classified as an all-alpha protein fold. The globin fold is found in its namesake globin families as well as in phycocyanins. The globin fold was thus the ...