Introduction to Amino Acids
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چکیده
Peptides made from a long chain of amino acids (AAs) that linked to their neighbors via covalent bonding form a peptide bond. More than 300 amino acids exist in nature, but only make up the proteins found in the human body. Amino acids received considerable attention due to their biological significance. They contain two important functional groups: ─NH 2 and ─COOH, and an interesting side chain on the carbon that connected the amino group to the carboxyl group. Amino acids are traditionally classified as nutritionally essential and nonessential for animals and humans ( Scheme 1.1 ). Of the 20 amino acids, 9 are termed essential because the body cannot ably synthesize and they must be supplied through food sources. Essential amino acids include phenylalanine, valine, threonine, tryptophan, methionine, leucine, isoleucine, lysine, and histidine. Scheme 1.1 Essential and nonessential amino acids. The structural formulas of the 20 standard amino acids. Each acid includes an amino group, a carboxyl group, and a distinct side chain. Structures have sulfur atoms in methionine and cysteine, ring shapes in phenylalanine, tyrosine, and tryptophan, a special ring in proline, amide groups in asparagine and glutamine, acidic parts in aspartic and glutamic acid, and basic parts in lysine, arginine, and histidine. https://www.w3.org/1999/xlink" content-type="black-white" specific-use="print-only" xlink:href=" https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781003615422/2d9c782c-8116-4256-a7f6-a27a7f054a91/content/fig1_3_PB.tif "/> https://www.w3.org/1999/xlink" content-type="colour" specific-use="web-only" xlink:href=" https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781003615422/2d9c782c-8116-4256-a7f6-a27a7f054a91/content/fig1_3_OC.tif "/>