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Ribbon diagrams, also known as Richardson diagrams, are 3D schematic representations of protein structure and are one of the most common methods of protein depiction used today. The ribbon depicts the general course and organization of the protein backbone in 3D and serves as a visual framework for hanging details of the entire atomic structure ...
The words protein, polypeptide, and peptide are a little ambiguous and can overlap in meaning. Protein is generally used to refer to the complete biological molecule in a stable conformation, whereas peptide is generally reserved for a short amino acid oligomers often lacking a stable 3D structure. But the boundary between the two is not well ...
Protein primary structure is the linear sequence of amino acids in a peptide or protein. [1] By convention, the primary structure of a protein is reported starting from the amino-terminal (N) end to the carboxyl-terminal (C) end. Protein biosynthesis is most commonly performed by ribosomes in cells. Peptides can also be synthesized in the ...
This is the topic of the scientific field of structural biology, which employs techniques such as X-ray crystallography, NMR spectroscopy, cryo-electron microscopy (cryo-EM) and dual polarisation interferometry, to determine the structure of proteins. Protein structures range in size from tens to several thousand amino acids. [2]
[1] [2] A polypeptide is a longer, continuous, unbranched peptide chain. [3] Polypeptides that have a molecular mass of 10,000 Da or more are called proteins . [ 4 ] Chains of fewer than twenty amino acids are called oligopeptides , and include dipeptides , tripeptides , and tetrapeptides .
According to one definition, a turn is a structural motif where the C α atoms of two residues separated by a few (usually 1 to 5) peptide bonds are close (less than 7 Å [0.70 nm]). [1] The proximity of the terminal C α atoms often correlates with formation of an inter main chain hydrogen bond between the corresponding residues.
When Pauling and Corey first proposed the alpha sheet, they suggested that it agreed well with fiber diffraction results from beta-keratin fibers. [2] However, since the alpha sheet did not appear to be energetically favorable, they argued that beta sheets would occur more commonly among normal proteins, [3] and subsequent demonstration that beta-keratin is made of beta sheets consigned the ...
In order to maintain a standard for Cell and molecular biology articles a standard color scheme should be used. The accepted colors for cellular locations are described in the table. Colors for other components, such as molecules, can be chosen at the discretion of the designer, however, the following should be considered: