> See also: > - [[Translation]] > - [[Protein Structure]] > - [[Protein Conformational Changes]] # Amino Acids > [Amino Acid Study Guide: Structure and Function](https://www.albert.io/blog/amino-acid-study-guide-structure-and-function/) > [Isoelectric Points of Amino Acids (and How To Calculate Them)](https://www.masterorganicchemistry.com/2023/02/09/isoelectric-point-calculation/) > [Amino Acid - ChemTalk](https://chemistrytalk.org/amino-acid-chart/) ![[Pasted image 20240225094131.png|200]] At the lowest level, proteins are composed of individual amino acid subunits which form a longer polypeptide chain - There are 20 “proteinogenic” amino acid building blocks (plus selenocysteine) that can be encoded by the human genome and incorporated into - Humans can only synthesize 12 of them, the 8 others must be provided by commensal bacteria The alpha carbon is a stereocenter, with L and D form amino acids being its enantiomers. - L form is found within cells - D form still plays a - Because the R group of glycine is another hydrogen, it is the only amino acid that no longer contains a chiral center. #### Amino Acid Classifications ![[Amino Acids-1.png|300]] Based on the properties of their side chain, amino acids are classified into **polar** and **non-polar**. The polar amino acids are further subdivided into **charged** and **uncharged**. - This charge only refers to the charge of the side chain, not the whole amino acid structure - In this case, the charge state of the side chain group is under physiological conditions (neutral pH). The non-polar group can be further divided as well: - Aliphatic: relating or denoting organic compounds in which carbon atoms form open chains (alkanes) not aromatic rings - Aromatics > [!NOTE]- Amino Acid Table > ![[Pasted image 20230922125915.png]] > [!NOTE]- Amino Acid pKa Chart > ![[amino acid pka chart.png]] - lysine is an epsilon amine - arginine has a guanidino group - QaNDE (COOH and Amide) > [!summary] Amino Acid Notable Functions > Serine > - Serine proteases > > Glutamine > - Capable of binding to and “recognizing” adenine > > aaa > -