As you know, proteins are a necessary and basic component of any living organism. They are responsible for metabolism and energy conversion, which are inextricably linked with almost all life processes. The dry matter of the vast majority of tissues and organs of animals and humans, as well as more than 50% of all microorganisms, mainly consists of proteins (from 40% to 50%). At the same time, in the plant world, their share is less than the average value, and in the animal world - more. However, the chemical composition of proteins for many people is still unknown. Let's once again remember what is inside these high molecular weight natural polymers.
Protein composition
This substance contains on average about 50-55% carbon, 15-17% nitrogen, 21-23% oxygen, 0.3-2.5% sulfur. In addition to the listed main components, sometimes proteins contain elements whose specific gravity is very small. First of all, it is phosphorus, iron, iodine, copper and some other micro and macro elements. Curiously, the concentration of nitrogen has the greatest constancy, whilethe content of other key components may vary. Describing the composition of a protein, it should be noted that it is an irregular polymer built from amino acid residues, the formula of which in a water solution at neutral pH can be written in the most general form as NH3+CHRCOO-.
These "bricks" are connected to each other by an amide bond between carboxyl and amine groups. In total, about a thousand different proteins have been identified in nature. This class includes antibodies, enzymes, many hormones and other active biological substances. Surprisingly, with all this diversity, the composition of a protein can include no more than 30 different amino acids, 20 of which are the most popular. Only 22 of them are contained in the human body, while the rest are simply not absorbed and are excreted. Eight amino acids from this group are considered essential. These are leucine, methionine, isoleucine, lysine, phenylalanine, tryptophan, threonine and valine. Our body cannot synthesize them on its own, and therefore they need to be supplied from outside.
The rest (taurine, arginine, glycine, carnitine, asparagine, histidine, cysteine, glutamine, alanine, ornithine, tyrosine, proline, serine, cystine) he can create on his own. Therefore, these amino acids are classified as non-essential. Depending on the presence of the first group of proteins in the composition, as well as on the degree of its absorption by the body, the protein is divided into complete and inferior. The average daily intake of this substance for a person lies in the range from 1 to 2grams per kilogram of weight. At the same time, sedentary people should adhere to the lower limit of this range, and athletes - the upper one.
How protein composition is studied
To study these substances, the hydrolysis method is mainly used. The protein of interest is heated with dilute hydrochloric acid (6-10 mol/litre) at 100°C to 1100°C. As a result, it will break down into a mixture of amino acids, from which individual amino acids are already isolated. Currently, paper chromatography as well as ion-exchange chromatography are used for the quantitative analysis of the protein under study. There are even special automatic analyzers that easily determine which amino acids are formed as a result of breakdown.
