Amino acids proteinogenic modified

The 20 proteinogenic amino acids have become key building blocks as chiral pool materials. In addition to these 20 amino acids, there are many analogues with modified sidechains, backbones, or different stereochemistry. Some of these other amino acids, such as D-alanine, are found in nature, but in this chapter they will be collected under the descriptor of unnatural amino acids. 

The process of protein biosynthesis is called translation. Post-translational oxidation, alkylation and esterification of some amino acids that are bound in proteins yield modified proteinogenic amino acids (see Section 2.2.1.1.2). Non-proteinogenic (non-encoded, non-standard or secondary) amino acids do not function as building blocks of proteins, as they have other roles in organisms. Amino acids also have an influence on the organoleptic properties of food, especially on their taste. Products of reactions of amino acids are often important compounds influencing odour, taste and colour of foods. 

Extensive work on the tag-and-modify approach has been carried out by the Davis group, ° spanning from the modification of a cysteine tag to the inclusion of non-proteinogenic amino acids (e.g. dehydroalanine,... 

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