WHAT ARE PROTEINS? WHAT IS THEIR FUNCTION IN BODY?

Next to water, proteins is the most abundant component of the body. There are thousands of different specific proteins in the body, each having a unique structure and functions. For this reason, protein implies not one but a large group of complex compounds. Proteins are in all living tissues, both plant animals. They form a part of the nucleus and protoplast of every cell

COMPOSITION :
Proteins are very large organic compounds. They contain carbon, hydrogen and oxygen, in addition proteins contain about 16% nitrogen, which is their unique feature and distinguishes them from carbohydrates and fats, some proteins contain sulphur, Iron, and cobalt, phosphorous. Proteins are synthesized by the plant from the nitrates and ammonia in the soil. Herbivorous animals use plant proteins to meet their proteins needs. Man use both plant and animal foods to meet to the protein needs.
All proteins in the body and food are build from basis units or compounds known as amino acids. Amino acids combine to form protein by means of a peptide bond , which joins a carboxylic carbon of one amino acid with nitrogen of another.

Based on composition proteins are classified into 3 types:
 Simple proteins
 Conjugated proteins
 Derived proteins

Simple proteins
Simple proteins yield amino acids on hydrolysis
Example: albumins, globulins and albuminoids are simple proteins.
Conjugated proteins
Conjugated proteins are combinations of simple proteins with non-protein substance they includes
 Lipoproteins
 Nucleoproteinss
 Phosphoproteins
 Metalloproteins
Derived proteins:
Derived proteins are proteoses, and peptides formed in the various stages of protein metabolism.

THE BUILDING BLOCKS OF PROTEINS ARE AMINO ACIDS:
Essential amino acids:
There are 22 or more amino acids, all of which are vital to human live and health. The body is able to synthesize. 13 of these but is unable to make nine other. These nine have to be provided in the diet in sufficient amounts and are called essential amino acids.
 Isoleucine
 Lysine
 Methionine
 Phenylalanine
 Threonine
 Tryptophan
Non- essential amino acids:
The word non –essential is misleading for these are necessary in the body for tissue building, repair and other metabolic functions. These are so important the body synthesizes them itself. The only these are termed non-essential is because these need not be provided in the diet.
 Glycine
 Alanine
 Serine
 Aspartic acid
 Glutamic acid
 Cystine
 Proline
 Hydroxyproline
 Tyrosine

Function of proteins
The primary function of proteins is tissue building, proteins are the main solid matter in the matter; they are also the major constituents of blood, matrix of bones, teeth, skin, nails and hair.
Body-building or building of new tissues:
The amount of protein needed at various stages of life varies with the rate of growth. Infants need more proteins per unit of body weight than adolescent, because the rate of growth is the highest is during infancy. More protein needed in the last part of pregnancy as compared to the first part.
There an extra need of protein, to rebuild tissues after their loss or destruction. The loss may occur in any one of the following ways.
Donation of blood
Excessive menstruation
Hemorrhage after an accident
Destruction of tissue due to burns, in wasting diseases such as TB rheumatic fever .

Maintenance of tissues:
All body proteins are constantly being degraded and synthesized at varying rates. For example the lining of the intestinal tract is renewed everyone and a half, proteins in the liver and blood plasma is broken and remade every six days, blood cells have life of 120 and adequate must be supplied to prevent anemia. Thus there is need for protein to provide for maintenance of tissues already built

Regulatory functions:
Hemoglobin ensures the smooth running of the respiratory cycle by being the vital oxygen carries in the red blood cells.
Proteins in fluids such as blood help to regulate body processes. Plasma protein contributes to osmotic pressure and thus exert an important influence on the exchange of water between tissue cells and the surrounding fluids and on the water balance of the body.

Proteins as precursors of enzymes, hormones and antibodies:
Small amount of protein or amino acid is needed for the synthesis of all these. All enzymes are protein and are essential catalysts in digestion and metabolic processes in the tissues.
Hormones , secreted by various glands are proteins in nature. Hormones regulate and co-ordinates body processes and activities.

Best food sources of protein | Best protein rich foods
Plants are the primary source of protein, because they can synthesize protein by combining nitrogen and water from the soil and carbon dioxide from the air.
Pulses
Whole wheat
Nuts
Oilseeds
Milk
Eggs
Fish
Poultry
And meat
These are the good source of proteins