In chemistry, an amino acid is any molecule that contains both amine and carboxyl functional groups. In biochemistry, this term refers to alpha amino acids. These alpha amino acids are components of proteins. In proteins, amino acids are joined together in a chain by peptide bonds between their amino and carboxylate groups. An amino acid residue is one amino acid that is joined to another by a peptide bond. Each different protein has a unique sequence of amino acid residues, this is its primary structure.
There are 20 standard amino acids used by cells in protein biosynthesis. These 20 amino acids can be biosynthesised from simpler molecules, but organisms differ in how many they are able to produce and essential amino acids must be obtained in their diet.
Amino acids in proteins: Amino acids are the basic structural building units of proteins. 20 amino acids are encoded by the standard genetic code and are called proteinogenic or standard amino acids.
Non-protein amino acids: Hundreds of types of non-protein amino acids have been found in nature and they have multiple functions in living organisms. In humans, non-protein amino acids also have biologically-important roles. Glycine, gamma-aminobutyric acid and glutamate are neurotransmitters and many amino acids are used to synthesize other molecules.
Essential & Non-Essential Amino Acids
From 20 standard proteinogenic amino acids, 10 are called essential amino acids because the human body cannot synthesize them from other compounds through chemical reactions, and they therefore must be obtained from food.
An essential amino acid or indispensable amino acid, is an amino acid that cannot be synthesized de novo by the organism (usually referring to humans), and therefore must be supplied in the diet. They are: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. In addition, the amino acids arginine, cysteine, glycine and tyrosine are considered conditionally essential, meaning they are not normally required in the diet, but must be supplied exogenously to specific populations that do not synthesize it in adequate amounts.
The distinction between essential and non-essential amino acids is somewhat unclear, as some amino acids can be produced from others. Which amino acids are essential varies from species to species, as different metabolisms are able to synthesize different substances.
Foodstuffs that lack essential amino acids are poor sources of protein equivalents, as the body tends to deaminate the amino acids obtained, converting proteins into fats and carbohydrates. Therefore, a balance of essential amino acids is necessary for a high degree of net protein utilization, which is the mass ratio of amino acids converted to proteins to amino acids supplied.
Amino Acid Supplements
Athletes take amino acid supplements to increase muscle bulk. However, amino acid supplements are often prescribed as a medical treatment during the recovery period after serious illnesses, traumas or burns and scalds. These supplements are also used as the treatment for metabolic diseases and immunodeficiency. Here is the list of common used amino acid supplements:
To learn more about each of the amino acid supplement, click a corresponding link above.
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