File Name: 20 amino acids and their structures and functions .zip
Proteinogenic amino acids are amino acids that are incorporated biosynthetically into proteins during translation. The word "proteinogenic" means "protein creating". Throughout known life , there are 22 genetically encoded proteinogenic amino acids, 20 in the standard genetic code and an additional 2 that can be incorporated by special translation mechanisms. In contrast, non-proteinogenic amino acids are amino acids that are either not incorporated into proteins like GABA , L -DOPA , or triiodothyronine , misincorporated in place of a genetically encoded amino acid, or not produced directly and in isolation by standard cellular machinery like hydroxyproline. The latter often results from post-translational modification of proteins. Some non-proteinogenic amino acids are incorporated into nonribosomal peptides which are synthesized by non-ribosomal peptide synthetases. Both eukaryotes and prokaryotes can incorporate selenocysteine into their proteins via a nucleotide sequence known as a SECIS element , which directs the cell to translate a nearby UGA codon as selenocysteine UGA is normally a stop codon.
Amino acids are organic compounds that contain amino —NH 2 and carboxyl —COOH functional groups , along with a side chain R group specific to each amino acid. About naturally occurring amino acids are known as of though only 20 appear in the genetic code and can be classified in many ways. In the form of proteins , amino acid residues form the second-largest component water is the largest of human muscles and other tissues. In biochemistry , amino acids which have the amine group attached to the alpha- carbon atom next to the carboxyl group have particular importance. They include the 22 proteinogenic "protein-building" amino acids,    which combine into peptide chains "polypeptides" to form the building blocks of a vast array of proteins.
Basic Structure of Amino Acids. Introduction Essential amino acids Why learn this? Amino acids play central roles both as building blocks of proteins and as intermediates in metabolism. The 20 amino acids that are found within proteins convey a vast array of chemical versatility. The precise amino acid content, and the sequence of those amino acids, of a specific protein, is determined by the sequence of the bases in the gene that encodes that protein.
Side chains (R groups): group amino acids by structure and function. (Assignment: memorize amino acids by name, side chain, abbreviations, characteristic).
Amino acids, as ancient and ubiquitous molecules, have been co-opted by evolution for a variety of purposes in living systems. The importance in reading this section is limited to those who wants to visualize the structures. The common amino acids are known as a-amino acids because they have a primary amino group -NH2 and a carboxylic acid group -COOH as substitutes of the a carbon atoms. Proline is an exception because it has a secondary amino group -NH- , for uniformity it is also treated as alpha-amino acid. Fig 1. General structure of a- amino acid.
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. Amino acids IMGT classes of the 20 common amino acids Amino acid abbreviations, characteristics, volume and hydropathy index Charge, hydrogen donor and acceptor atoms, and polarity of the amino acid side chains. Formula of the 20 common amino acids Structural details of the side chains: formula, 3D model and atoms nomenclature. Formula of the 20 common amino acids The formula of an amino acid comprises, bound to a carbon alpha carbon : a carboxyl group -COOH an amine group -NH2 an atom of hydrogen -H a variable radical -R, that is the functional group in red in the table of the amino acid. The 20 common amino acids are grouped in classes according to their side chains: Click here for IMGT classes of the 20 common amino acids 'Physicochemical' properties.
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.
All of the proteins on the face of the earth are made up of the same 20 amino acids. Linked together in long chains called polypeptides, amino acids are the building blocks for the vast assortment of proteins found in all living cells. All amino acids have the same basic structure, which is shown in Figure 2. With the exception of glycine, which has an R-group consisting of a hydrogen atom, all of the amino acids in proteins have four different groups attached to them and consequently can exist in two mirror image forms, L and D.
The formula of a general amino acid is:. In addition to their role as protein building blocks in living organisms, amino acids are used industrially in numerous ways. The first report of the commercial production of an amino acid was in
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