The Basic Substance of Human Body --- Protein
As we know, protein is the basic substance of living forms. No life can live without protein. So it has a close link to other life and living forms. Every cell and important tissue of human body have the participation of protein. From 15% to 20% of human’s weight is protein, which means that an adult with 50kg has protein of 7.5kg to 10kg. There are a variety of proteins in human body and they have different shapes and functions. But most of them are made of more than twenty kinds of amino acids in different proportions and they can have metabolism and update consistently.
What is the characteristics of protein?
First, protein is ambidextrous. It is the macromolecular compound which is made by peptide and amino acids. Protein molecules contain both amino and carboxyl, so it is same as amino acids.
Second,protein can have the hydrolysis reaction.The hydrolysis reaction will happen through the stimulation of acid, alkali or enzyme and finally it become several kinds of amino acids. It is advised to find the breaking point of tissues when the protein is under the hydrolysis.
Third, it owns the features of colloid when it melt in water.Some kinds of proteins can melt in water and form solution. For example, egg whites can melt in water. If the diameter molecular of proteins is same as that of colloidal particles, it will have the features of colloidal.
Fourth, protein precipitation. Adding neutral salts with high concentrations, heavy metal,alkaloids or acids can promote the dissolution of the protein. If add concentrated inorganic salt solution into protein solution, the solubility of protein can be reduced and it will separate out from solution.It is called salting out. The protein which is through salting out also can melt in water and has no effect on its primary features, so it salting out a reversible process. This method can be used to separation and purification of proteins.
How to identify protein? It will produce a specific smell of burning feathers when burn protein. That can be used to identify protein.