Biochemistry

Amino acids are classified in accordance with the chemical structure into acyclic (aliphatic), aromatic, heterocyclic-, by the number of amine and carboxyl groups in the molecule - into monoaminomonocarboxylic, diaminomonocarboxylic, monoaminodicarboxylic, diaminodicarboxylic. According to the modem rational classification based on the polarity of radicals, 4 classes of amino acids are distinguished: 1) non-polar or hydrophobic-, 2) polar (hydrophilic) uncharged', 3) negatively charged-, 4) positively charged at physiological pH values (at pH 6.0 - 7.0). Table 2.3 presents the classification of proteinogenic amino acids, it shows the historical and rational names, structural formula and abbreviations of amino acids accepted in domestic and foreign literature Table 23 - Classification of amino acids Name | Structure | Abbreviation I. Nonpolar or hydrophobic amino acids 1. L-Alanine (a-aminopropionic acid) CH 3 - CH-COOH 1 NHz Ala 2. L-Valine (a - aminoisovaleric acid) H,C JCH-CH-COOH HC Z 1 NH, Vai 3. L-Leucinc (a - aminoisocaproic acid) HA CH-CH.-CH-COOH HC Z 1 3 nh 2 Leu 4. L-Isoleucine (a-amino-P-methyl- valeric acid) CH, CH»-CH 1 -CH-CH-COOH 1 NH, He 5. L-Tryptophan (a-amino-P- indolylpropionic acid) ------ r- CH,-CH-COOH UU NH 2 Try 6. L-Proline (pyrrolidine-a- carboxylic acid) L J-COOH NH Pro 7. L-Phenylalanine (a-amino-P- phenylpropionic acid) 0 r* CH 2 — CH-COOH Phe 40