Amino Acids - The Building Blocks For The Human Body
Amino acids represent the basic building block for protein. Although there are hundreds of amino acids located in the body there are 20 that are encoded with the standard genetic code and they are normally referred to as proteinogenic or standard amino acids. These 20 amino acids are listed and described below: Alanine Alanine also called 2-aminopropanoic acid is considered to be a non-essential a-amino acid. Instead it exists as two distinct enantiomers - L-alanine and D-alanine. L-alanine is one of the 20 amino acids most widely used in protein synthesis, second to leucine, accounting for 7.8% of the primary structure in a sample of 1,150 proteins. D-alanine occurs in bacterial cell walls and in some peptide antibiotics. Arginine Arginine is an a-amino acid. The L-form is one of the 20 most common natural amino acids. In mammals, arginine is classified as a semiessential or conditionally essential amino acid, depending on the developmental stage and health status of the individual. Asparagine Asparagine is one of the more common and natural amino acids. It has carboxamide as the side chains's functional group. It is viewed as a non-essential amino acid. It was one of the first amino acids to be isolated and was obtained form asparagus juice. Aspartic Acid Aspartic acid sometimes known as aspartate, which is the name of its anion, is one of the 20 natural proteingenic amino acids. As a neurotransmitter, aspartic acid may provide resistance to fatigue and an increase in endurance. Cysteine Cysteine is a naturally occurring hydrophobic amino acid which has a thiol group and is found in small quantities in most proteins. When it is exposed to air it oxidizes to form cystine, which is two cysteine molecules joined by a disulfide bond. N-acetyl-L-cysteine (NAC) is derived from cysteine and is a popular dietary supplement that is metabolized into the antioxidant glutathione. Glutamic acid Glutamic acid also called glutamate (the anionic form) is one of the 20 standard amino acids used by all organisms in their proteins. Glu is critical for proper cell function, but it is not an essential nutrient in humans because it can be produced from other compounds. Glutamine Glutamine is one of the 20 amino acids encoded by the standard genetic code. Its side chain is an amide; it is formed by replacing a side-chain hydroxyl of glutamic acid with an amine functional group. Glycine Glycine is a nonpolar amino acid. It is the simplest of the 20 standard (proteinogenic) amino acids: its side chain is a hydrogen atom. Because there is a second hydrogen atom at the a carbon, glycine is not optically active. Most proteins contain only small quantities of glycine. A notable exception is collagen, which is about one-third glycine. Histidine Histidine is one of the 20 most common natural amino acids present in proteins. In the nutritional sense, in humans, histidine is considered an essential amino acid, but mostly only in children. Isoleucine Isoleucine is one of the 20 standard amino acids, and is coded for in DNA. Its chemical composition is identical to that of leucine, but the arrangement of its atoms is slightly different, resulting in different properties. Nutritionally, in humans, isoleucine is an essential amino acid. Isoleucine is a hydrophobic amino acid. Alanine Leucine is the most common amino acid found in proteins. It is essential for optimal growth in infancy and childhood and for nitrogen equilibrium in adults. It is suspected that Leucine plays a part in maintaining muscles by equalizing synthesis and breakdown of proteins. Lysine Lysine with its 4-aminobutyl side-chain, it is classified as a basic amino acid, along with arginine and histidine. It is an essential amino acid, and the human nutritional requirement is 1-1.5 g daily. A deficiency in lysine can result in a deficiency in niacin (which is a B Vitamin). This can cause the disease pellagra. Lysine can also be used as a nutritional supplement to help against herpes. Methionone Methionine is an essential nonpolar amino acid and a lipotropic. Improper conversion of Methionone can lead to atherosclerosis. Foods containing methionine include fruits, meat, vegetables, nuts and legumes. High levels of methionine can be found in spinach, green peas, garlic, some cheeses, corn, brazil nuts, pistachios, cashew nuts, kidney beans, black turtle beans, tofu, and tempeh. Most meat is also a rich source of Methionine including chicken, beef and fish. Phenylalanine Phenylalanine exists in two forms, the D- and L- forms, which are enantiomers (mirror-image molecules) of each other. Phenylalanine is used in living organisms, including the human body, where it is an essential amino acid. L-phenylalanine can also be converted into L-tyrosine, another one of the twenty protein-forming amino acids. The genetic disorder phenylketonuria is an inability to metabolize phenylalanine. Individuals with this disorder are known as "phenylketonurics", and must abstain from consumption of phenylalanine. It is present in many sugarless gums and other food products, which are labeled: "Phenylketonurics: Contains phenylalanine." Proline Proline is one of the twenty proteinogenic units which are used in living organisms as the building blocks of proteins. The other nineteen units are all primary amino acids, but due to the (3-carbon) cyclic sidechain binding back to the nitrogen of the backbone, proline lacks a primary amine group (-NH2). The nitrogen in proline is properly referred to as a secondary amine. Proline is sometimes called an imino acid, but this is not correct, as imines contain a carbon-nitrogen double bond. The side chain binding to the nitrogen prevents rotation around the phi torsion angle, giving proline unique structural properties. Serine Serine is one of the 20 amino acids commonly found in animal proteins. Only the L-stereoisomer appears in mammalian protein. It is not essential to the human diet, since it can be synthesized in the body from other metabolites, including glycine. Serine was first obtained from silk protein, a particularly rich source, in 1865. Its name is derived from the Latin for silk, sericum. Serine's structure was established in 1902. Threonine Threonine is one of the 20 natural amino acids that in humans in nutritionally an essential amino acid. Foods high in threonine are cottage cheese, poultry, fish, meat, lentils, and sesame seeds. Tryptophan Tryptophan is an amino acid and essential in human nutrition. It is one of the 20 amino acids in the genetic code. Only the L-stereoisomer appears in mammalian protein. Tryptophan is an essential amino acid that humans cannot live without consuming snd has been implicated as a possible cause of schizophrenia in people who cannot metabolize it properly. When improperly metabolized, it creates a waste product in the brain that is toxic, causing hallucinations and delusions. Tryptophan has also been indicated as an aid for schizophrenic patients. Tyrosine Tyrosine is derived from the Greek word tyros, meaning cheese, as it was first discovered in cheese), 4-hydroxyphenylalanine, or 2-amino-3(4-hydroxyphenyl)-propanoic acid, is one of the 20 amino acids that are used by cells to synthesize proteins. It has a phenol side chain. Valine Valine is the last of the 20 natural amino acids and is coded for in DNA. It is also considered an essential amino acid. In sickle-cell disease, it substitutes for the hydrophilic amino acid glutamic acid in hemoglobin: Because valine is hydrophobic, the hemoglobin does not fold correctly. Foods that are good sources of valine include cottage cheese, fish, poultry, beef, peanuts, sesame seeds, and lentils. As you can probably guess these amino acids are very complex and are vital to some aspects of a healthy life. Additional information on Amino Acids can be found at Wikipedia - The Free Encyclopedia.
