Proteins of plants are poorer than proteins of an animal origin on a of irreplaceable amino acids, a lysine, methionine, tryptophane. Proteins of soy and potatoes on an amino-acid are closest to proteins of animals. Absence in a stern of irreplaceable amino acids to heavy violations of a nitrogenous exchange. Therefore selection of grain crops is directed, in particular, and on improvement of quality of proteinaceous composition of grain.
The groups which are a part of the radical of R amino acids can enter a with each other, with foreign substances and with proteinaceous and other molecules, forming difficult and structures.
In a macromolecule of protein one or several chains connected with each other cross by communications, most often through a (disulfide bridges, the remains cysteine. The chemical structure of peptide chains can be primary a squirrel or a sequence.
Normal activity of an organism is possible at continuous receipt of food. The fats which are a part of food, proteins, carbohydrates, mineral salts, water and vitamins are necessary for vital processes of an organism.
Proteins, fats and carbohydrates are called as nutrients. These substances are necessary components of food. In a digestive tract of a squirrel, fats and carbohydrates are exposed both to physical impacts (are crushed and fray), and to chemical changes which happen under the influence of special substances - the enzymes containing in juice of digestive glands. Under the influence of digestive juice nutrients are split on simpler which are soaked up and acquired by an organism.
Proteins - irreplaceable construction material. One of the most important functions of proteinaceous molecules is plastic. All cellular membranes support squirrels which role is various here. The amount of protein in membranes makes more than a half of weight.
Their very various are explained by a structure of proteins. They have different solubility: some are dissolved in water, others — in the diluted solutions of neutral salts, and some do not possess property of solubility at all (for example, proteins of integumentary fabrics). At dissolution of proteins in water a peculiar molecular-disperse system (solution high-molecular substances is formed. Some proteins can be in the form of crystals (protein of egg, blood hemoglobin).
Regulatory function is carried out also by the squirrels containing in a thyroid gland - tireoglobulina which molecular weight about 60000 of These squirrels contain iodine in the structure. At an underdevelopment of gland the metabolism is broken.
The following important property is that enzymes are in fabrics and cages in an inactive form (pro-enzyme. Its classical examples are inactive forms of pepsin and trypsin. Existence of inactive forms of enzymes has great biological value. If pepsin was developed at once in an active form, pepsin "digested" a stomach wall, i.e. the stomach "digested" itself.
One of important and interesting hormones in the chemical relation is. It suppresses a mocheobrazovaniye and raises a blood pressure. Vazopressin is a cyclic structure with a lateral chain:
The role of proteins in transport of substances in an organism is great. Having functional various groups and complex structure of a macromolecule, proteins connect and transfer many connections with blood current. It first of all the hemoglobin transferring oxygen from lungs to cages. In muscles this function is assumed by one more transport protein - a.
The main nitrogen-containing substances of which proteins consist, are amino acids. The amount of amino acids is small - them only 2 All enormous variety of the proteins containing in the nature is known represents various combination of known amino acids. Properties and qualities of proteins depend on their combination.
Many proteins possess sokratitelny function. It first of all proteins and a, entering muscle fibers of the higher organisms. Muscle fibers - miofibrilla - represent the long thin threads consisting of the parallel thinner muscular threads surrounded with intracellular liquid. In it the adenosine triphosphoric acid (ATP) necessary for reduction implementation, a glycogen - nutrient, inorganic salts and many other substances, in particular calcium are dissolved.