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Function Of Proteins - Amino Acids - and Branched Chain Amino Acids

Updated on March 9, 2012

Building and Repairing of Body Tissues

Amino acids are the main building blocks of proteins. Amino acids are also intermediates players in body metabolism. Proteins serve in building and repairing of body tissues as well as a source of energy for the body. In particular, proteins play the following role in our bodies:

Function of Proteins

1. proteins are used in forming antibodies that enable the body to fight infection that are called antigens (foreign invaders)

2. Proteins such as casein and ovalbumin are important to the body as they are useful in storing of amino acids. Casein is the main protein found in milk, and in coagulated form in the cheese. Ovalbumin is the main protein found in egg white.

3. Hemoglobin is a protein that is used by the body in transporting oxygen in the body through the blood. Oxygen is what the body cells use to convert glucose into energy.

4. Contractile proteins such as myosin aids in contraction of muscles and body movements.

5. Enzymes are proteins that are used by the body in speeding up digestion of food.

6. Hormones are proteins which are regulatory substances produced in the body and transported in tissue fluids such as blood or sap to stimulate specific cells or tissues into action. For example insulin is a hormone that regulates the amount of glucose in the blood and lack of insulin in the body will cause diabetes.

7. Proteins such as keratin, collagen, and elastin are used in the formation of body structure and support. For example Keratins are used by the body in strengthening hair and nails whilst collagens and elastin are used by the body in providing support for connective tissues such as tendons and ligaments.

Synthesize of Various Proteins

Proteins therefore plays a major role in ensuring the health well being of our bodies. The function of protein in our bodies is determined by the structure of the protein. And the structure of protein is mainly determined by the type of amino acid building the protein. It’s the amino acids that are used by our bodies to synthesize various proteins.

Amino acids - Amino acids are the building blocks of protein. Image Credit:YassineMrabet Yassine Mrabet via Wikimedia
Amino acids - Amino acids are the building blocks of protein. Image Credit:YassineMrabet Yassine Mrabet via Wikimedia | Source

Nine Essential Amino Acids for Humans

Naturally, there are nine standard amino acids called essential amino acids for humans. They are called essential because our bodies can not create them from other compounds. These essential amino acids have to be taken by human body in as food. The nine essential amino acids for humans are:

1. Histidine - an essential amino acid found in proteins that is important for the growth and repair of tissue. Good sources of histidine include dairy, meat, poultry, fish as well as rye, rice, and wheat.

2. Isoleucine - One of the three branched chain amino acids. Foods rich in isoleucine include eggs, soy protein, seaweed, turkey, chicken, lamb, cheese, and fish.

3. Leucine - a white crystalline amino acid occurring in proteins that is essential for nutrition and which is obtained by the hydrolysis of most dietary proteins

4. Lysine - an essential amino acid found in proteins and which is mainly obtained from gelatin and casein

5. Methionine - Important for growth, healthy nails and skin and main sources of methionine are eggs, sesame seeds, Brazil nuts, fish, meats.

6. Phenylalanine - needed for growth of children and for protein metabolism in children and adults. Sources of Phenylalanine are mainly milk and eggs

7. Threonine - essential component of human nutrition and main sources include cottage meat, lentils, cheese, poultry, fish, and sesame seeds.

8. Tryptophan - an essential amino for growth and normal metabolism which is a precursor of niacin. Tryptophan helps lift your mood. Sources of Tryptophan include chocolate, oats, milk, yogurt, cottage cheese, red meat, eggs, fish, poultry, sesame, sunflower seeds, pumpkin seeds, bananas, and peanuts.

9. Valine is an essential amino acid which is important for growth in children and nitrogen balance in adults. Its main sources are dairy, meat, grain, mushrooms, soy and peanuts.

Branched Chain Amino Acids (BCAAs)

From these nine essential amino acids which must be taken in food, three of these amino acids are called Branched Chain Amino Acids (BCAAs). The Branched Chain Amino Acids are:

1. Leucine

2. Isoleucine

3. Valine

Branched Chain Amino Acids for Increased Exercise Efficiency

The branched chain amino acids accounts for 35% of the essential amino acids in muscle proteins. The branched chain amino acids also accounts for 40% of the preformed amino acids required by our bodies. The branched chain amino acids are of special importance in that they are metabolized in the muscle, rather than in the liver as is the case for the other essential amino acids. Branched chain amino acids are therefore very significant for increased exercise efficiency due to the improved levels of aerobic and anaerobic capacity of the body. Branched-chain amino acids are also used to help slow muscle wasting as well as preventing prevent fatigue and to improve one’s ability to concentrate.

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    • Jerrico Usher profile image

      Jerrico Usher 

      6 years ago from Bend, Oregon

      fascinating post, thanks for bringing it to hubpages!

    • jhunpaler profile image


      6 years ago from Philippines

      This article brings me back to my biochemistry days, amino acids and proteins are important building blocks in their body, a single impairment in their DNA could cause trouble. Thanks for the informative hub


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