Proteins: what they are
Proteins - a high molecular weight organic compounds.They are constructed from carbon atoms, oxygen, hydrogen and nitrogen, but they may also contain sulfur, iron and phosphorus.
protein monomers are amino acids joined together by peptide bonds.Polypeptides may have a large number of amino acids in their composition and have a larger molecular weight.
molecule consists of an amino acid radical, an amino group -NH2, and a carboxyl group -COOH.The first group shows the basic properties, the second - acid.This makes the dual nature of the chemical behavior of amino acids - its amphoteric and moreover, high reactivity.Different parts of the amino acids together in a chain of protein molecules. radical (R) - is the part of the molecule, which is different for different am
ino acids.It can have the same molecular formula but different structure.
functions of proteins in the body
Proteins perform several important functions in individual cells and throughout the body as a whole.
First of all proteins have a structural function.Because these molecules are constructed membranes and cell organelles.Collagen - an important component of connective tissue, keratin part of the hair and nails (and feathers and horns of animals), the elastic protein elastin is needed to ligaments and blood vessel walls.
Equally important is the role of the enzyme protein.By the way, all biological enzymes are protein nature.Thanks to them possible biochemical reactions in the body acceptable to the pace of life. enzyme molecule may consist of only proteins or also include non-protein compound - coenzyme.As coenzymes are most often vitamins or metal ions.
transport function of proteins is carried out thanks to their ability to bind with other substances.Thus, hemoglobin binds oxygen and transports it from the lungs to the tissues, myoglobin carries oxygen to the muscles.Serum albumin carries blood lipids, fatty acids and other biologically active substances. carrier proteins are near cell membranes and transports substances through them.
protective function is performed by the organism-specific proteins.Antibodies produced by lymphocytes are struggling with foreign proteins, interferons protect against viruses.Thrombin and fibrinogen contribute to the formation of a blood clot and prevent the body from blood loss. toxins from living beings for defensive purposes, also have protein in nature.The target organism to suppress the action of these poisons produced antitoxins.
regulatory functions performed regulatory proteins - hormones.They control the flow of physiological processes in the body.Thus, in the blood glucose level corresponds to insulin, and its lack of diabetes occurs.
Proteins sometimes perform and energy function, but are not the main energy.Complete cleavage of 1 gram of protein gives 17.6 kJ of energy (as in the breakdown of glucose).However, protein compounds are too important for the body to build new structures and as an energy source is used very rarely.