Proline

L-Proline is one of the twenty amino acids (formerly, proline was misleadingly called an imino acid) that are used by living organisms as a building block of proteins (so called proteinogenic amino acids).

In proteins, proline can act as a structural disruptor for (α) helices, and as a turning point in β sheets. Multiple prolines in a row can create a proline helix. Sequences of proline and 1-Aminoisobutyric acid (Aib) form a helical turn structure.

Incorporated into peptides proline forms a tertiary amide. It does not have a hydrogen on the amide group and can therefore not act as a hydrogen bond donor.

Data :

• Chemical formula: NH₈C₅O₂
• Molecular weight : 115.13
• Isoelectric point : 6.30
• van der Waals volume : 90
• pK1 (α-COOH): 1.95
• pK2 (αN-H): 10.64
• Protein Occurance: 5.2%

See also : biochemistry