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Protein before and after folding Results of 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. [1]
Biomolecular structure is the intricate folded, three-dimensional shape that is formed by a molecule of protein, DNA, or RNA, and that is important to its function.The structure of these molecules may be considered at any of several length scales ranging from the level of individual atoms to the relationships among entire protein subunits.
Proteins also have structural or mechanical functions, such as actin and myosin in muscle and the proteins in the cytoskeleton, which form a system of scaffolding that maintains cell shape. Other proteins are important in cell signaling, immune responses , cell adhesion , and the cell cycle .
Although the ribbon cartoon is the most common way of displaying a protein structure, a protein whose surface shape clearly affects its function may best be shown as a surface. For example, a surface representation may help demonstrate the contours of a binding pocket or size of a membrane protein pore.
Its shape can change in response to changes in its environment or other factors; each possible shape is called a conformation, and a transition between them is called a conformational change. Factors that may induce such changes include temperature, pH , voltage , light in chromophores , concentration of ions , phosphorylation , or the binding ...
Globular proteins are somewhat water-soluble (forming colloids in water), unlike the fibrous or membrane proteins. [1] There are multiple fold classes of globular proteins, since there are many different architectures that can fold into a roughly spherical shape. The term globin can refer more specifically to proteins including the globin fold. [2]
The diagram sketches how proteins fold into their native structures by minimizing their free energy. The folding funnel hypothesis is a specific version of the energy landscape theory of protein folding, which assumes that a protein's native state corresponds to its free energy minimum under the solution conditions usually encountered in cells.
Protein structure databases are critical for many efforts in computational biology such as structure based drug design, both in developing the computational methods used and in providing a large experimental dataset used by some methods to provide insights about the function of a protein.