Protein is a very important place in our body. The word ‘Protein’ is derived from the Greek word ‘Proteas’ which means ‘primary importance’. Jons Jakob Berzelius discovered it in 1838.
1/4 part of body weight is composed of protein. It is one of the basic building blocks of the human body and is present in every single cell.
It is essential for the maintenance of the body tissues, including development and repair in children, teens, and pregnant women, proper immune system function, digestion, hair, and nail growth, and also involved in other body functions.
What is Protein?
Protein is a micronutrient that is made up of smaller units called amino acids. It is also called primary foodstuffs. It is an organic compound composed of a chemical combination of carbon, hydrogen, oxygen, and nitrogen.
Protein also contains sulfur, phosphorus, iodine, and iron in less amount. The presence of nitrogen in protein distinguishes it from carbohydrates and fats that make it unique energy-providing nutrients.
Proteins can be found in both animal and plant foods. When intake proteins from the foods, they are broken down into smaller parts called amino acids during digestion in our bodies.
What are Amino acids?
Amino acids are the organic nutrients that are found in the food as well as in the human body, either in the form of building blocks of proteins or as free amino acids.
All the amino acids have a basic skeleton which is made up of carbon linked to an amino group (NH2), a carbonyl group (COOH), a side chain containing carbon, oxygen, or hydrogen atom.
The bond which connects the amino group of one amino acid to the carbonyl group of another amino group is called a peptide bond. This bond is also called the covalent bond.
When several amino acids are linked together by the peptide bonds, a polypeptide chain is formed. Large amounts of amino acids need to maintain good health in the human body.
Types of Amino acids
Amino acids have been mainly divided into three groups. They are as follows:
1. Essential amino acids: Proteins naturally found in the form of 21 amino acids. Out of 21 amino acids, 9 for adults and 10 for children are important for maintaining human health.
These amino acids are called essential amino acids. The important essential amino acids are Valine, Histidine, Isoleucine, Leucine, Threonine, Lysine, etc. The human body can not produce them.
So, we have to get essential amino acids from foods. They also provide a source of energy like proteins, which provide about 4 calories per gram.
2. Non-essential amino acids: Non-essential amino acids are formed due to the normal breakdown of proteins in the body. Examples of important non-essential amino acids are Alanine, Asparagine, Aspartic acid, Serine, etc.
These amino acids are not required to take from our daily diet because our bodies can develop it in the presence of nitrogen.
3. Conditional amino acids: Conditional amino acids are essential at the time of illness and stress. Some examples of conditional amino acids are Arginine, Glycine, and Tyrosine.
Types of Proteins
Generally, Proteins fall into one of three types. They are:
1. Globular Proteins: They act as enzymes, chemical signaling compounds, transporters of other compounds, and antibodies. Hemoglobin is an example of globular proteins.
Myoglobin is another example of a globular protein. It is used to store the oxygen in muscle tissue. Albumin is another example of a globular protein. It is the amplest protein in human blood plasma.
Its biological functions include transporting hormones, fatty acids, and acts as a buffer and maintaining osmotic pressure.
2. Fibrous Proteins: Fibrous proteins play important roles in providing structural rigidity and in contractile movement. An example of a fibrous protein is collagen. It is a strong, fibrous protein made up of mostly glycine and proline amino acids.
Collagen is the most abundant protein in the body and makes up 30 percent of bone tissue and comprises large amounts of tendons, ligaments, cartilage, skin, and muscles. Its function is to provide structural rigidity and stiffness.
It is found in skin, ligaments, tendons, and other parts of the body. It makes the bone strong and flexible. Keratins are other examples of fibrous proteins. Hair, skin, and nails are made of keratins.
3. Membrane Proteins: Membrane proteins function as enzymes, cell recognition, receive chemical signals between the interior and exterior of cells, and transports the chemical signals in and out of cells.
An example of membrane proteins is Aquaporins. Aquaporins act as transporter proteins. They facilitate the transport of water molecules in and out of cells.
Classification of Proteins
Classification of protein based on source:
We can divide protein into two types on the basis of sources. They are:
1. Animal Protein: This is of high-level protein that gets from animals. Its sources are meat, fish, egg, milk, and dishes made from milk.
2. Vegetable Protein: Protein obtained from plants are called vegetable proteins. These are generally medium or low-grade protein. Sources of low-grade protein are wheat, rice, maize, sorghum, and millet.
Protein derived from peas, cowpea, peanuts, and dried fruits are of moderate grade. Protein obtained from soybean are high grade.
Classification of protein based on nutrition value:
We can also do the classification of protein on the basis of the ratio and quantity of amino acids getting in foods.
1. Complete Protein: Essential amino acids that are found in the proper amounts and proportion are called complete protein. This protein is essential for the right growth and development of the body. The complete proteins are found in milk, meat, fish, egg, soybean, and some dried fruits.
2. Partially Complete Protein: The essential amino acids that are less in quantity in foods are called partially complete protein. These proteins are helpful in keeping the body alive, but not in general intelligence and development. Proteins obtained from grains, dals, and vegetables are partially complete proteins.
3. Incomplete Proteins: Proteins obtained from fruits and vegetables are called incomplete protein. In the incomplete protein, the number and quantity of essential amino acids are very less from which our body is not grown.
Classification on the basis of chemical composition:
1. Simple Protein: Such proteins give only amino acids after aqueous decomposition. For example, Globulin in milk, Albumin in egg, keratin in hairs.
2. Conjugated Protein: In this, amino acids and any other substance are present. For example:
- Hemoglobin ⇒ Heme (iron) + globin (protein)
- Lipoprotein ⇒ Fat + Protein
3. Derived Protein: This protein is not found naturally. It is produced during the process of enzymes and digestion in our digestive system. For example, Peptone and Peptide.
Functions of Proteins in our body
Proteins take part in different types of functions in the body. They are as follows:
1. Formation of enzymes: Enzymes are proteins that conduct specific chemical reactions in the body. An enzyme’s function is to provide a site for substances to chemically react and form a product.
Enzymes help to conduct chemical reaction with lower the amount of energy and time. This process is called catalysis.
In every single second, on average, more than one hundred chemical reactions occur in cells and most of them require enzymes. Alone, the liver contains over one thousand enzyme systems.
2. Hormones: Proteins are responsible for hormone synthesis. Hormones are the chemical messages which are produced by the endocrine glands. When an endocrine gland is stimulated, it releases a hormone, and then it is transported in the blood to its target cell, where it communicates a message to initiate a specific reaction or cellular process.
For example, after eating foods, our blood glucose levels increase. In response to the increased blood glucose, the pancreas releases the hormone called insulin.
Insulin tells cells of the body that glucose is available and takes it from the blood and store it for making energy or building macromolecules. Hormones play a very important role to turn enzymes on and off.
3. Transport: Albumin and hemoglobin play an important role in molecular transport. Albumin chemically binds to hormones, fatty acids, some vitamins, essential minerals, and transports them throughout the circulatory system.
Each red blood cell (RBC) contains millions of hemoglobin molecules that bind oxygen in the lungs and transport it to all the tissues in the body.
4. Energy: Proteins provide a good source of energy. It contains 4.2k calories of energy per gram protein. If a person’s diet contains more proteins than the body needs, the body will use it for energy.
If you do not take a sufficient amount of carbohydrates and fats, your body will use more amino acids to make energy, which compromises the synthesis of new proteins and destroys the muscle proteins.
But if you intake extra proteins than the body needs, the extra amino acids will be broken down and transformed into fats.
5. Antibodies: Antibodies are the glycoproteins that help to prevent infection, diseases, and illness. These proteins help to destroy harmful bacteria and viruses. The antibodies are secreted by the white blood cells that search the entire circulatory system for harmful bacteria and viruses to surround and destroy them.
They also act as a trigger for other factors in the immune system to seek and to destroy unwanted intruders.
6. Body Building: The most important function of protein is physical development. The formation of new cells is happened by proteins for the growth of any organ.
7. Repair of tissues: The primary function of protein is to repair tissues of the body. Protein is required for any part of the body to be cut, burnt, repaired, and rebuilt.
8. Blood clotting: Fibrinogen is a glycoprotein involved in the healing of wounds. For example, when you get an injury from a needle of sewing, your flesh is turned red and becomes inflamed.
Within a few seconds, the bleeding would stop. The healing process starts with proteins such as bradykinin, which enlarge blood vessels at the site of injury. An additional protein called fibrin helps to form a clot to stop the bleeding.
9. Maintaining pH balance: Protein is also essential in maintaining proper pH balance in the blood. The pH level in the blood is preserved between 7.35 and 7.45, which is slightly basic. If a slight change in blood pH occurs, then it will affect your body’s functions.
10. Regulation of body processes: Proteins help to maintain acid-base balance in the body. It also makes the temperature of the body steady.
How are Proteins important in maintaining our body healthy?
Proteins are vital in maintaining our body healthy because of the following reasons. They are:
1. Healthy hair: The main problem of hair fall is also a protein deficiency. When there is a lack of protein in our daily diets, our body starts saving proteins instead of using it in hair growth.
Our hair does not get adequate proteins for growth due to which so many problems are started such as hair loss, hair thinning, hair dry, and hair whitening. So if you want to prevent your hair fall, you must take enough proteins in your daily diets.
2. Brain Power: The protein intake in our diet also affects the performance of our brain because the protein provides essential signals to our brain’s Nero transmitter which helps it to function better. A Nero transmitter is a basically biochemical messenger that transmits signals to the brain cells. Proteins also improve your concentration power and memory.
3. Muscles building: If your muscles are not able to build or you have issues of muscle pain and weakness, it means that there is a shortage of protein in your diet.
Protein is essential for building, repairing, and maintaining muscles, ligaments, and body tissues. Protein is essential for growth and replacement of cells. Thus, proteins are essential for body growth and functioning.
4. Immunity: Due to the lack of proteins, the body’s immune system is also affected, causing the risk of diseases and infections. This is because immune cells of our body comprise proteins and also repair from proteins.
If you are getting sick frequently or you have frequent cough and cold, allergies, and infections, then this may be due to the lack of proteins. Therefore, we should take adequate proteins in your daily diet and keep healthy and strong.
5. Metabolism: Proteins regulate metabolism. They make 12-15% of diet calories. Proteins provide the base for manufacturing enzymes, hormones, antibodies, etc.
6. Risk of Bone Fractures: Our bones are also affected due to a lack of proteins. Insufficient protein intake may weaken your bone and increase the risk of fractures. Therefore, you should take enough proteins to maintain the strength and density of bones.
7. Increased Severity of Infection: Insufficient protein intake can also increase the risk of infection in your body. Eating too little protein decreases the ability to fight against infections.
8. Energy: Protein is a source of energy. If you take one gram of protein, it will provide you with 4.2 kilocalories of energy.
Sources of Protein
High-protein foods:
- Meat, fish, eggs, beans, bread, nuts and seeds, milk, soybeans, etc.
Low protein foods:
- Legumes, green peas, vegetables, rice, wheat, peanut butter, etc.
How many grams of proteins need per day?
Since hair, skin, eyes, muscles, and organs are all made up of proteins. So, a high-quality proteins diet is essential for maintaining a healthy body. The recommended daily allowance of proteins for a woman is 46 grams/day, whereas for men is 56 grams per day.
The protein requirement for children are:
- Age 0 to 6 months: 9 grams per day.
- Age 7 to 12 months: 11 grams per day.
- Age 1 to 3 years: 13 grams per day.
- Age 4 to 8 years: 19 grams per day.
- Age 9 or older: 36 grams per day.
What is Protein Deficiency? What is effects of deficiency of protein?
When your intake of proteins from food does not fulfill the requirement of sufficient protein in your body, it is called protein deficiency. An estimated one billion people worldwide are suffering from inadequate protein intake. In India, 9 out of 10 Indian people are protein deficient.
If we are talking about Urban Indian, around 73% diet is protein deficient whereas 84% of vegetarian diets are low on protein as against as non-vegetarian diets.
The most severe form of protein deficiency is Kwashiorkor and Marasmus, which mostly occur in children in developing countries.
Kwashiorkor: This disease mostly occurs in children until 1 to 5 years. There are two reasons that kwashiorkor occurs in children.
- To prematurely release the milk of mother in children.
- Lack of nutrition and quantity of proteins in the food.
Marasmus: This disease mostly occurs in children under 15 months. It generally occurs because of both lack of calories and proteins.
Signs and Symptoms of Protein Deficiency
Protein deficiency can affect all the functions of the body. There are 12 signs and symptoms of protein deficiency. We list them below:
- Low energy levels.
- Trouble building muscles.
- Trouble learning.
- Poor concentration.
- Muscle, bone, and joint pain.
- Hair fall, Baldness.
- Low immunity
- Losing weight
- Irregular Periods.
- Sluggish Metabolism
- High Cholesterol
- Slow wound healing
If you are experiencing any of these problems, then it is the time to check your diets.
In this tutorial, you have known about proteins and its classification, functions, sources, etc. Hope that you will have understood all the basic points of proteins and enjoyed this tutorial.
Thanks for reading!!!
