Tertiary structure intramolecular interactions

The conformation of a protein is determined and maintained by a range of intramolecular interactions 

It should be appreciated that amino acids such as serine, threonine, tyrosine, and cysteine all contain side-chain alcohol or thiol groups that may participate in hydrogen bonding and stabilize a particular protein conformation. 

With some proteins, there is a further level of structure, i.e. quaternary structure, which may 

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What kinds of intramolecular interactions are important in stabilizing a protein s tertiary structure ... 

The ribosomal RNAs are involved in multiple molecular interactions with both protein factors and other RNAs in addition to having an extensive intramolecular secondary structure of their own. These interactions involve not only particular sequence domains but also recognition of secondary and tertiary structural features of the RNA molecule.1-12 Un-... 

Intramolecular hydrogen bonds between different components of molecules stabilize conformation. They are among the most important interactions in small and in large biological molecules because they require particular molecular conformations to be formed, and when formed, they confer additional rotational stability to these conformations. They ultimately help to determine and to define the three-dimensional structures of the molecules, and are therefore involved in their functional aspects. These bonds are of major importance in the globular proteins, where all the secondary and tertiary structure hydrogen bonds are of this type. In polypeptides, the NH 0=C bonds between peptide bonds (n) and (n+3) give rise to / -turns and to 310 helices, and between bonds (n) and (n+4) to a-helices (see Part III, Chapt. 19). 

Tertiary structure (of a protein) the overall shape of a protein, long and narrow or globular, maintained by different types of intramolecular interactions. (22.6)... 

Tertiary structure involves the intramolecular folding of the polypeptide chain into a compact three-dimensional structure with a specific shape. This structure is maintained by electrovalent linkages, hydrogen bonds, disulfide bridges, van der Waals forces, and hydrophobic interactions. Hydrophobic interactions are considered to be a major force in maintaining the unique tertiary structure of proteins. 

All enzymes are proteins, which are linear sequences of amino acids linked by peptide bonds. The folding of these sequences determined the secondary structure (such as a-helix, p-sheet or p-turn) and tertiary structure. Therefore, the properties of an en me are actually presumed from its sequence of amino acids. Some amino acids, dubbed hot spots , especially the ones in the active site where substrate binds, are sensitive to catalytic properties of an enzyme. Substitution of these important amino acids can significantly improve the activity or enantioselectivity toward a certain reaction. Protein stability is also maintained by the intramolecular and intermolecular interactions between residues of amino acids, including van der Waals forces, hydrophobic forces, electrostatic forces, hydrogen bonds and disulfide bonds. Detailed analysis of these amino acids, usually located in the protein surface, sheds light on the protein design for better thermostability. 

Many important systems and processes, especially biological assemblies such as cell walls and protein secondary and tertiary structures form as a result of physical, inter- and intramolecular interactions. Such assemblies and... 

Amino acids are chiral substances. Usually only one of the enantiomers is found to be biologically active. Protein structure is determined by the sequence of amino acids in the chain (its primary structure), the intramolecular interactions within the chain (its secondary structure), and the overall shape of the complete molecule (its tertiary structure). Two important secondary structures are the a-helix and the /3-sheet. The process by which a protein assumes its biologically active tertiary structure is called folding. Sometimes several proteins aggregate together to form a quaternary structure. 

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