Amino acids are the basic unit that combines together to form the protein. Each amino acid is joined by a specific type of covalent bond called a peptide bond. There are a total of 300 amino acids present in nature out of which only 20 types of amino acids are found in proteins.
Proteins and amino acids are called the building block of our body. The amino acid has two functional groups which are an amino group and a carboxyl group. The basic constituent of amino acid is nitrogen which comes from atmospheric nitrogen which is very stable because of its triple bond.
A nitrogen atom has 7 electrons, 2 in the innermost shell and 5 in the outermost cell. To obtain a stable configuration, the atom needs 3 more electrons in the outermost cell. A nitrogen atom fills its outer octet by sharing electrons with another nitrogen atom to get a total of 8 electrons in the outermost shell, thus forming three covalent bonds.
As the nitrogen atom obtains its stable configuration it becomes difficult to break the triple bond. Nitrogenase, an enzyme helps break the triple bond so that the nitrogen atom can form a new compound that will be useful for the body. Through this enzymatic reaction, N2 gets converted to NH3, which can be used by the body in the formation of amino acid.
Role of Amino Acids in Our Body
The amino acid plays a very crucial role in several biological processes. The most common of them is protein formation. Our body uses protein to repair tissues, make enzymes and hormones and is an important constituent in the building of muscles and bones. Protein is a macro element that is required by the body in a large amount.
About 16% of the weight of the protein is an amino acid. Egg, meat, beans, etc are rich in protein. When we consume these foods, the protein in them gets broken down during the digestion process into amino acids.
Different Categories of Amino acids
- Structure
- Metabolic fate
- Nutritional requirement
Seven Types of Amino Acids (Based on Structure)
- Amino acid with aliphatic side chain: Glycine, alanine, valine, leucine, isoleucine
- Amino acid-containing hydroxyl group: Serine, threonine, tyrosine
- Sulfur-containing amino acid: Cysteine, cysteine, methionine
- Acidic amino acids and their amides: Aspartic acid, asparagines, glutamic acid
- Basic amino acid: Lysine, arginine, histidine
- Aromatic amino acid: Phenylalanine, tyrosine, tryptophan
- Amino acids: Proline
Three Categories of Amino Acids (Based on Metabolic Rate)
- Glucogenic amino acid: the carbon skeleton of theses amino acids degrades to form glucose. Example alanine
- Ketogenic amino acid: fats and ketone bodies are formed when the carbon skeleton of amino acid is degraded. Example lysine
- Mixed function amino acids: the carbon skeleton degrades to form both glucose and ketone bodies. Example tyrosine
Two Groups of Amino acids (Based on Nutritional Requirement)
Essential Amino Acid
Essential amino acids or indispensable amino acid, include those amino acids which are not present in our body and we need to take them through our diet. A total of nine amino acids are included in this category some of which are histidine, leucine, and lysine. These amino acids are predominantly found in food such as asparagus, beans, spinach, sprouts and meet.
Non-Essential Amino Acid
Non-essential amino acids are those amino acids that are already present in our body and we do not necessarily need them in our diet. This includes serine, cysteine, asparagines, alanine, etc.
The amino acid is also a part of neurotransmitters. Neurotransmitters are the chemical substances that help transfer signals from one region to another. There are two types of synapse, one is electrical synapse where ions play the role in the transfer of messages and the other is chemical synapse which uses neurotransmitters such as glycine, glutamate and GABA which are made up of amino acids.
Amino acids play a pivotal role in the growth of the body. It is said that athletes take amino acid supplements to increase their ability to perform, increase their endurance and strength. As we know that amino acids are the constituents that make protein, thus amino acid supplements help build muscle mass, and repair damaged tissues.
Amino acid supplements are completely safe for consumption, though a person should ask the professionals for the recommended dosage. These supplements should not be used by diabetics, kidney patients and amyotrophic lateral sclerosis patients.
Hormones for Growth
Hormones play a very important role in growth, metabolism, and fertility. These are chemical messengers that are produced in the multi-cellular organism to carry out certain functions of the body. These chemical messengers are secreted by exocrine and endocrine glands. The exocrine glands are those glands that secrete their hormones into ducts and endocrine glands are those glands which release the hormones directly into the bloodstream. Hormones are grouped into three types amines, proteins and peptides which are basically long chains of amino acids, and steroids. Hormones such as epinephrine and norepinephrine are derived from Tyrosine and tryptophan which in turn are derived from amino acids.
Tyrosine is responsible for the production of melanin, which is a pigment that gives color to the skin, hair and eyes. After many researches the function of melanin is still not confirmed but it is said that melanin pigment protects the skin from harmful UV rays from the sun, which can cause skin cancer. This pigment is present in more concentration in darker people than in fairer people. Another function of tyrosine is to control important brain functions and regulate mood. Tyrosine also contributes to the production of dopamine, which in turn increases concentration. Dopamine is also called the feel-good hormone.
The neurotransmitter serotonin is synthesized from tryptophan which is made up of amino acid. This neurotransmitter plays a major role in the body. It regulates mood, social behavior, appetite, digestion, sleep and memory. In addition, it also regulates the body’s sleep-wake cycle and the internal clock. Serotonin is linked with depression, though it is unclear whether a lower level of serotonin is the reason for depression or not. But there are some drugs that alter the levels of serotonin and are used for medical purpose to treat depression, migraine and nausea.
Deficiency or Excess of Amino Acids
The deficiency of amino acid can be due to some inherited disorder which can mess up the biochemical mechanisms of the body or poor diet following with stress. The deficiency of amino acid can cause mental and physical health issues such as depression, mood swings, lack of concentration, bloating, slower metabolism, can hamper growth in the child and weaker immune system. You can easily overcome the deficiency by eating food rich in protein. There are both animal and plant-based food products which can help you overcome the deficiency. Animal-based food includes meat, milk, egg, fishes, etc and plant-based food includes soy, bean, sprouts, spinach, etc.
Amino acids can be harmful if produced or taken in excess. The excess of amino acid in the system can cause increase risk of gout which can ultimately lead to the build-up of uric acid leading to inflammation in the joints, drop in blood pressure, change in eating habits and can potentially damage the kidney as the unusual levels of amino acids cause strain in the kidney as it has to work harder to maintain the required levels, etc.
Take a balanced diet, exercise regularly to keep your body healthy. Consult a doctor if you feel like you have any symptoms of the deficiency and get the necessary supplements.
