File Name: 20 amino acid and their structures .zip
An aromatic amino acid AAA  is an amino acid that includes an aromatic ring. Among the 20 standard amino acids, the following are aromatic: phenylalanine , tryptophan and tyrosine. However, in addition to being aromatic, tyrosine can be classified as a polar amino acid.
In addition, while histidine contains an aromatic ring, its basic properties cause it to be predominantly classified as a polar amino acid; however, the compound is still aromatic. Aromatic amino acids absorb ultraviolet light at a wavelength above nm and produce fluorescence.
This characteristic is used in quantitative analysis, notably in determining the concentrations of these amino acids in solution. However, because several aromatic amino acids exist, this method has low accuracy; in order to mitigate this issue, the desired protein must be pure, and its molar absorptivity is known.
In addition, a protein without aromatic amino acids will not have an absorption maximum at approximately nm. The presence of nucleic acids in the protein can further decrease the method's accuracy due to the presence of purine and pyrimidine rings, which have an absorption maximum at approximately nm.
Phenylalanine has a relatively weak absorbance in comparison to the other standard aromatic amino acids; its presence in a protein can only be detected if tryptophan and tyrosine are not present.
Tryptophan has the highest relative absorbance in comparison to the other standard aromatic amino acids; its absorption maximum occurs at nm. The absorption maximum of tyrosine occurs at nm.
In plants, the shikimate pathway first leads to the formation of chorismate , which is the precursor of phenylalanine, tyrosine, and tryptophan. These aromatic amino acids are the derivatives of many secondary metabolites , all essential to a plant's biological functions, such as the hormones salicylate and auxin. This pathway contains enzymes that can be regulated by inhibitors, which can cease the production of chorismate, and ultimately the organism's biological functions.
Herbicides and antibiotics work by inhibiting these enzymes involved in the biosynthesis of aromatic amino acids, thereby rendering them toxic to plants. In addition to destroying greens, Glyphosate can easily affect the maintenance of the gut microbiota in host organisms by specifically inhibiting the 5-enolpyruvylshikinatephosphate synthase which prevents the biosynthesis of essential aromatic amino acids.
Inhibition of this enzyme results in disorders such as gastrointestinal diseases and metabolic diseases. Aromatic amino acids often serve as the precursors to other molecules. For instance, in the production of epinephrine, phenylalanine is the starting molecule. The reaction is indicated below:. Tyrosine is also a precursor for the synthesis of octopamine and melanin in numerous organisms.
In addition, histidine is the precursor to histamine. Tryptophan is the starting molecule in the synthesis of tryptamine, serotonin, auxin, kynurenines, and melatonin. Animals obtain aromatic amino acids from their diet, but all plants and micro-organisms must synthesize their aromatic amino acids through the metabolically costly shikimate pathway in order to make them.
Phenylalanine , tryptophan , and histidine are essential amino acids for animals. Since they are not synthesized in the human body, they must be derived from the diet. Tyrosine is semi-essential; therefore, it can be synthesized by the animal, but only from phenylalanine.
Phenylketonuria , a genetic disorder that occurs as a result of the inability to breakdown phenylalanine, is due to a lack of the enzyme phenylalanine hydroxylase. A dietary lack of tryptophan can cause stunted skeletal development.
It could be caused by other factors as well such as the use of various herbs and foods like chocolate which inhibit monoamine oxidase enzymes to varying degrees, and also some medications. Aromatic trace amines like tyramine can displace norepinephrine from peripheral monoamine vesicles and in people taking MAOIs this occurs to the extent of being life threatning. From Wikipedia, the free encyclopedia.
Logan's Medical and Scientific Abbreviations. Philadelphia: J. Lippincott Company. Biochemistry and Molecular Biology Education. Retrieved Frontiers in Molecular Biosciences.
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Genetics Home Reference. National Library of Medicine. Metabolism map. Carbon fixation. Photo- respiration. Pentose phosphate pathway. Citric acid cycle. Glyoxylate cycle. Urea cycle. Fatty acid synthesis. Fatty acid elongation. Beta oxidation. Glyco- genolysis. Glyco- genesis. Glyco- lysis. Gluconeo- genesis. Pyruvate decarb- oxylation. Keto- lysis. Keto- genesis. Light reaction. Oxidative phosphorylation.
Amino acid deamination. Citrate shuttle. MVA pathway. MEP pathway. Shikimate pathway. Glycosyl- ation. Sugar acids. Simple sugars. Nucleotide sugars. Propionyl -CoA. Acetyl -CoA. Oxalo- acetate. Succinyl -CoA. Ketone bodies. Respiratory chain. Serine group. Branched-chain amino acids. Aspartate group. Amino acids. Ascorbate vitamin C. Bile pigments. Cobalamins vitamin B Various vitamin Bs.
Calciferols vitamin D. Retinoids vitamin A. Nucleic acids. Terpenoid backbones. Bile acids. Glycero- phospholipids. Fatty acids. Glyco- sphingolipids. Polyunsaturated fatty acids.
Download the PDF version. Increasingly, drug developers are looking to large molecules, particularly proteins, as a therapeutic option. Formulation of a protein drug product can be quite a challenge, and without a good understanding of the nature of protein structure and the conformational characteristics of the specific protein being formulated, the results can be ruinous. This technical brief aims to give the reader a quick overview of protein structure. It will also cover briefly how protein structure can be affected during formulation and some of the analytical methods which can be used both to determine the structure and analyze the stability of the protein.
•Proteins are synthesized from the set of 20 L-α-amino acids •Mixed amino acids: There are aa, carbon skeleton of which catabolized to.
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Chemically speaking, an amino acid is a carboxylic acid which has an amine group attached to it. The general formula of an amino acid is composed by a carbon alpha atom, a carboxyl group, a side chain group and an amino group.
Although there are hundreds of amino acids found in nature, proteins are constructed from a set of 20 amino acids. Generally, amino acids have the following structural properties:. All amino acids have the alpha carbon bonded to a hydrogen atom, carboxyl group, and amino group. The "R" group varies among amino acids and determines the differences between these protein monomers. The amino acid sequence of a protein is determined by the information found in the cellular genetic code.
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