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The tertiary structure is dependent on the interaction of secondary structure,
quaternary typically formed by combining multiple molecules with tertiary
structure.
The secondary structure of proteins formed by the interaction of amino
acids by hydrogen bonding and hydrophobic interactions. The main types of
secondary structure are
- A - helix when hydrogen bonds occur between amino acids in a single
chain,
- В - sheets (layers folded) when hydrogen bonds are formed between
different polypeptide chains extending in different directions (antiparallel)
- Disordered areas.
For predicting secondary structure are used computer programs. Tertiary
structure or "fold" formed by the interaction of secondary structures and is
stabilized by non-covalent, ionic, hydrogen bonds and hydrophobic interactions.
Proteins generally perform similar functions have similar tertiary structure.
An example of a fold p-Burrell (barrel), when p-sheets are arranged in a circle.
The tertiary structure of proteins is determined by X-ray analysis.
An important class of polymeric protein is fibrous proteins, the most
famous of which is collagen.
In the animal world as a reference, structure-forming polymer proteins
usually act.
These polymers are built of 20 a-amino acids. amino acid residues in the
protein macromolecule linked by peptide bonds that result from the reaction of
carboxyl and amino groups.
The value of proteins in nature can not be overestimated. This building
material of living organisms, biocatalysts - enzymes providing the reactions in
cells and enzymes that stimulate certain biochemical reactions, i.e. provide
biocatalysis the selectivity. Muscle, hair, human skin is composed of fibrous
proteins.
A blood protein, a part of hemoglobin, promotes the absorption of
atmospheric oxygen, other protein - Insulin - responsible for the cleavage of
sugar in the body and therefore its energy security.
The molecular weight of protein varies widely. Thus, insulin - the first of
the protein structure which could set F. Sanger in 1953, contains about 60 amino
acid units, and its molecular weight is only 12,000.
To date, thousands of molecules identified several proteins with a
molecular weight of some of them reaches 106 or more.
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