Protein tertiary structure

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This diagram (which is interactive) of protein structure uses PCNA as an example. (PDB: 1AXC)

Tertiary Structure of a Protein — The tertiary structure of a protein consists of the way a polypeptide is formed of a complex molecular shape. This is caused by R-group interactions such as ionic and hydrogen bonds, disulphide bridges, and hydrophobic & hydrophilic interactions.

Protein tertiary structure is the three-dimensional shape of a protein. The tertiary structure will have a single polypeptide chain "backbone" with one or more protein secondary structures, the protein domains. Amino acid side chains and the backbone may interact and bond in a number of ways. The interactions and bonds of side chains within a particular protein determine its tertiary structure. The protein tertiary structure is defined by its atomic coordinates. These coordinates may refer either to a protein domain or to the entire tertiary structure. A number of these structures may bind to each other, forming a quaternary structure.

Interactions in tertiary structure of proteins