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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. Image File history File links Portal. ... This article is about the class of chemicals. ... In general usage, de novo is a Latin expression meaning afresh, anew, beginning again. In USA Banking, a de novo bank is defined as a state member bank that has been in operation for five years or less. ...

Essentiality vs. conditional essentiality in humans

Nine amino acids are generally regarded as essential for humans: isoleucine, leucine, lysine, threonine, tryptophan, methionine, histidine, valine and phenylalanine. In addition, the amino acids arginine, cysteine, glycine, glutamine 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. An example would be with the disease phenylketonuria (PKU). Individuals living with PKU must keep their intake of phenylalanine extremely low to prevent mental retardation and other metabolic complications. However, phenylalanine is the precursor for tyrosine synthesis. Without phenylalanine, tyrosine cannot be made and so tyrosine becomes essential in the diet of PKU patients. Isoleucine is an α-amino acid with the chemical formula HO2CCH(NH2)CH(CH3)CH2CH3. ... Leucine is one of the 20 most common amino acids and coded for by DNA. It is isomeric with isoleucine. ... Lysine is one of the 20 amino acids normally found in proteins. ... Threonine is one of the 20 natural amino acids. ... Tryptophan is an essential amino acid involved in human nutrition. ... Methionine is an α-amino acid with the chemical formula HO2CCH(NH2)CH2CH2SCH3. ... Histidine is one of the 20 most common natural amino acids present in proteins. ... Valine is an amino acid that cannot be synthesized by humans, so it is considered an essential amino acid for human life. ... Phenyl alanine is an α-amino acid with the formula HO2CCH(NH2)CH2C6H5. ... Arginine (abbreviated as Arg or R)[1] is an α-amino acid. ... Cysteine is a naturally occurring, sulfur-containing amino acid that is found in most proteins, although only in small quantities. ... For the plant, see Glycine (plant). ... Glutamine is one of the 20 amino acids encoded by the standard genetic code. ... Tyrosine (from the Greek tyros, meaning cheese, as it was first discovered in 1846 by German chemist Justus von Liebig in the protein casein from cheese[1][2]), 4-hydroxyphenylalanine, or 2-amino-3(4-hydroxyphenyl)-propanoic acid, is one of the 20 amino acids that are used by cells... Phenylketonuria (PKU) is an autosomal recessive genetic disorder characterized by a deficiency in the enzyme phenylalanine hydroxylase (PAH). ...

Which amino acids are essential varies from species to species, as different metabolisms are able to synthesize different substances. For instance, taurine (which is not, by strict definition, an amino acid) is essential for cats, but not for dogs. Thus, dog food is not nutritionally sufficient for cats, and taurine is added to commercial cat food when the base ingredients do not meet the requirements of the cat, but not to dog food. Taurine, or 2-aminoethanesulfonic acid, is an organic acid that is a major constituent of bile, and can be found in lower amounts in the tissues of many animals including humans. ... Taurine, or 2-aminoethanesulfonic acid, is an organic acid that is a major constituent of bile, and can be found in lower amounts in the tissues of many animals including humans. ...

The distinction between essential and non-essential amino acids is somewhat unclear, as some amino acids can be produced from others. The sulfur-containing amino acids, methionine and homocysteine, can be converted into each other but neither can be synthesized de novo in humans. Likewise, cysteine can be made from homocysteine but cannot be synthesized on its own. So, for convenience, sulfur-containing amino acids are sometimes considered a single pool of nutritionally-equivalent amino acids. Likewise arginine, ornithine, and citrulline, which are interconvertible by the urea cycle, are considered a single group. This article is about the chemical element. ... Methionine is an α-amino acid with the chemical formula HO2CCH(NH2)CH2CH2SCH3. ... Homocysteine is a chemical compound with the formula HSCH2CH2CH(NH2)CO2H. It is a homologue of the naturally-occurring amino acid cysteine, differing in that its side-chain contains an additional methylene (-CH2-) group before the thiol (-SH) group. ... Arginine (abbreviated as Arg or R)[1] is an α-amino acid. ... Ornithine is an amino acid, whose structure is: NH2-CH2-CH2-CH2-CHNH2-COOH Ornithine is one of the products of the action of the enzyme arginase on L-arginine, creating urea. ... The chemical compound citrulline is an α-amino acid (AA). ... The reactions of the urea cycle. ...

Recommended daily amounts

The following table lists the recommended daily amounts for essential amino acids in humans, together with their standard one-letter abbreviations.^[1] In some cases, humans can use either of two amino acids, so only the total matters.

Taurine may be necessary to preserve arterial and collagen pliability at 2 mg/kg/day, small but needed (142 mg/day per 70 kg human).^{[citation needed]} Lysine is one of the 20 amino acids normally found in proteins. ... Isoleucine is an α-amino acid with the chemical formula HO2CCH(NH2)CH(CH3)CH2CH3. ... Valine is an amino acid that cannot be synthesized by humans, so it is considered an essential amino acid for human life. ... Threonine is one of the 20 natural amino acids. ... Tryptophan is an essential amino acid involved in human nutrition. ... Histidine is one of the 20 most common natural amino acids present in proteins. ... Arginine (abbreviated as Arg or R)[1] is an α-amino acid. ... Taurine, or 2-aminoethanesulfonic acid, is an organic acid that is a major constituent of bile, and can be found in lower amounts in the tissues of many animals including humans. ...

Use of essential amino acids

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^[2]. 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. A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... Deamination is the removal of an amine group from a molecule. ... For other uses, see FAT. Fats consist of a wide group of compounds that are generally soluble in organic solvents and largely insoluble in water. ... Lactose is a disaccharide found in milk. ... The net protein utilization, or NPU, is the ratio of amino acid converted to proteins to the ratio of amino acids supplied. ...

All essential amino acids may be obtained from plant sources, and even strict vegetarian diets can provide all dietary requirements, although most vegetarians may not be so thorough. Some believe that careful monitoring of nutrient levels is important in strict vegetarian diets, but there are virtually no cases of protein-deficiency among populations consuming adequate calories. The only common cases of protein-deficiency occur among populations that are chronically undernourished.^{[citation needed]}

The net protein utilization is profoundly affected by the limiting amino acid content (the essential amino acid found in the smallest quantity in the foodstuff), and somewhat affected by salvage of essential amino acids in the body. It is therefore a good idea to mix foodstuffs that have different weaknesses in their essential amino acid distributions. This limits the loss of nitrogen through deamination and increases overall net protein utilization.

Species T. aestivum T. boeoticum T. dicoccoides T. dicoccon T. durum T. monococcum T. spelta T. sphaerococcum T. timopheevii References:   ITIS 42236 2002-09-22 Wheat Wheat For the indie rock group, see Wheat (band). ... Lysine is one of the 20 amino acids normally found in proteins. ... For other uses, see Rice (disambiguation). ... Lysine is one of the 20 amino acids normally found in proteins. ... Varieties of soybean seeds, a popular legume The term legume has two closely related meanings in botany, a situation encountered with many botanical common names of useful plants whereby an applied name can refer to either the plant itself, or to the edible fruit (or useful part). ... Tryptophan is an essential amino acid involved in human nutrition. ... This article is about the maize plant. ... Lysine is one of the 20 amino acids normally found in proteins. ... Tryptophan is an essential amino acid involved in human nutrition. ... The Food and Agricultural Organisation of the United Nations (FAO) defines pulses as annual leguminous crops yielding from one to 12 grains or seeds of variable size, shape and colour within a pod. ... Methionine is an α-amino acid with the chemical formula HO2CCH(NH2)CH2CH2SCH3. ... Cysteine is a naturally occurring, sulfur-containing amino acid that is found in most proteins, although only in small quantities. ... For other uses, see Beef (disambiguation). ... Phenyl alanine is an α-amino acid with the formula HO2CCH(NH2)CH2C6H5. ... Tyrosine (from the Greek tyros, meaning cheese, as it was first discovered in 1846 by German chemist Justus von Liebig in the protein casein from cheese[1][2]), 4-hydroxyphenylalanine, or 2-amino-3(4-hydroxyphenyl)-propanoic acid, is one of the 20 amino acids that are used by cells... An egg is a body consisting of an ovum surrounded by layers of membranes and an outer casing of some type, which acts to nourish and protect a developing embryo. ... A glass of cows milk. ... Percentages are relative to US recommendations for adults. ... Methionine is an α-amino acid with the chemical formula HO2CCH(NH2)CH2CH2SCH3. ... Cysteine is a naturally occurring, sulfur-containing amino acid that is found in most proteins, although only in small quantities. ...

Mnemonics

Using the one letter designation shown above, mnemonic devices have been developed for students wanting or needing to memorize the essential amino acids. Previous devices have utilized the first letter of the amino acids name, and in general did not include arginine which is not always essential. One mnemonic device that has been used in the past is PVT TIM HALL.^[3] A mnemonic (AmE [] or BrE []) is a memory aid. ...

Another method uses the first letter of each essential amino acid to begin each word in a phrase, such as: "Any Help In Learning These Little Molecules Proves Truly Valuable."^[4] This method begins with the two amino acids that need some qualifications as to their requirements.

Note that these devices work by using the first letter of the actual amino acids name. Due to repetition of letters, several amino acids have one letter abbreviations that are different than their first letter (e.g. lysine is K). Thus the complete list of essential amino acids utilizing one-letter codes is MILKVWTHFR.

See also

• Essential nutrient
• Biological Value (BV)
• List of standard amino acids
• Protein Digestibility Corrected Amino Acid Score
• Protein

An essential nutrient is a nutrient required for normal body functioning that cannot be synthesized by the body. ... Biological Value or BV is a common method for measuring protein quality and biological utilization rates of protein for human and animal consumption. ... It has been suggested that this article or section be merged with Proteinogenic amino acid. ... Protein Digestibility Corrected Amino Acid Score (PDCAAS) is a method of evaluating the protein quality based on the amino acid requirements of humans. ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ...

References

For other uses, see Mnemonic (disambiguation). ...

External links

• Amino acid content of some vegetarian foods - In a meal, make sure at least one food has a low value in each row of the "Amount to meet RDA" column, at veganhealth.org
• Amino Acid Profiles of Some Common Feeds at Virginia Tech
• Molecular Expressions: The Amino Acid Collection - Has detailed information and crystal photographs of each amino acid. at Florida State University
• Supplemental Information on Amino Acids - Explains each amino acid and the effects they have within the body.