2.1.8.2. Absorbency Under Load (AUL) - BADA

1.3.2. Amino Acids as Building Blocks of Proteins
Amino acids are molecules containing both amino and carboxyl functional groups with the
general formula H2NCHRCOOH, where R is an aliphatic or aromatic organic substitute, as a
basic structural building units of proteins (Fig.3).
Table 1 shows the achieved 22 α-amino acids [18] from proteins which can be split into three
different groups on the basis of the structure of their side chains. Only 20 of the 22 α-amino
acids are utilized by cell for protein synthesizing. Two of them are synthesized by cell after
protein is obtained.
Figure 3. Chemical structure of α-amino acids [5]
The location of the side chains of amino acids of proteins are generally those that it would expect
from their polarities.
1- Residues with non-polar hydrophobic side chains, such as Valine, Leucine, Isoleucine,
Methionine and Phenylalanine, are found in the interior of the protein out of contact with the
aqueous solvent.
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