L-proline
Proline (IUPAC-IUBMB abbreviation: Pro and P) is an α-amino acid, and its L enantiomer is one of the 22 proteinogenic amino acids. It is encoded on messenger RNAs by the codons CCU, CCC, CCA, and CCG. Unique among proteinogenic amino acids, proline features a secondary amine instead of a primary one, resulting in a distinct geometry that tends to disrupt secondary protein structures such as α-helices and β-sheets.
Proline contributes to the formation of non-polar residues that, when polymerized, can generate various types of proteins within the polyproline family. The presence of multiple proline residues can lead to the formation of a proline helix, as observed in the structure of collagen, a fibrous protein that constitutes a major component of connective tissues in the body.
The proline ring is nearly planar, a characteristic that can be demonstrated by examining the bond angles within the proline ring. This unique geometry and behavior make proline a critical player in the structural and functional properties of proteins, contributing to their diverse and intricate architectures.
- Structural Impact: Proline's distinct geometry introduces kinks and turns in the peptide chain, affecting the overall structure and conformation of proteins. It serves as a key component in various structural motifs, contributing to the stability and flexibility of protein structures.
- Biological Significance: Beyond its structural role, proline is involved in numerous biological processes. It participates in protein-protein interactions, signaling pathways, and the regulation of enzyme activity, underscoring its significance in diverse cellular functions.
- Post-Translational Modifications: Proline undergoes various post-translational modifications, including hydroxylation, glycosylation, and phosphorylation. These modifications can influence protein function and localization, contributing to the dynamic regulation of cellular processes.
- Role in Collagen Formation: Proline is a major component of collagen, the most abundant protein in mammals. Collagen's unique triple-helical structure relies on proline's rigid conformation, providing strength and stability to connective tissues such as skin, tendons, and bones.
- Polyproline Helices: The presence of multiple proline residues in certain proteins can induce the formation of polyproline helices, which play crucial roles in protein-protein interactions, signaling cascades, and cytoskeletal dynamics, among other functions.
Accession Number : KLM0000308 This work is released into the public domain; please see our release statement.
Synonyms :
- L-PROLINE
- Pro
- P
Config Rule :
% 'L-proline'
config('L-proline',[
ring([
(nit(1,hyd&&hyd;),down)~,
(car(1,carboxyl(2)&&hyd;),left)~,
methandiyl(3),
methandiyl(4),
(methandiyl(5),left)~])]).
Smiles String :
[C@1H]-1([N@2H2+][C@2H2][C@2H2][C@2H2]-1)[C](=[O])[O-] 'L-proline'
Fischer Diagram :
Terminal :
% 'L-proline'
c(1,12,(0,chiral))-[c(3,left)~,c(2,right)~,n(1,up)~,h(3,down)~],
c(2,12,(0,nonchiral))-[c(1,left)~,o(1,nil)?,o(2,nil)?],
c(3,12,(0,nonchiral))-[c(4,left)~,c(1,right)~,h(4,up)~,h(5,down)~],
c(4,12,(0,nonchiral))-[c(5,left)~,c(3,right)~,h(6,up)~,h(7,down)~],
c(5,12,(0,nonchiral))-[n(1,left)~,c(4,right)~,h(8,up)~,h(9,down)~],
h(1,1,(0,nonchiral))-[n(1,right)~],
h(2,1,(0,nonchiral))-[n(1,down)~],
h(3,1,(0,nonchiral))-[c(1,up)~],
h(4,1,(0,nonchiral))-[c(3,down)~],
h(5,1,(0,nonchiral))-[c(3,up)~],
h(6,1,(0,nonchiral))-[c(4,down)~],
h(7,1,(0,nonchiral))-[c(4,up)~],
h(8,1,(0,nonchiral))-[c(5,down)~],
h(9,1,(0,nonchiral))-[c(5,up)~],
n(1,14,(1,nonchiral))-[h(1,left)~,c(5,right)~,h(2,up)~,c(1,down)~],
o(1,16,(-5.0E-01,nonchiral))-[c(2,nil)?],
o(2,16,(-5.0E-01,nonchiral))-[c(2,nil)?]
The Terminals for all the Config Rules are in Prolog Definite Clause Grammar (DCG) form.They can be checked in the Manual here.
The compound's PDB file can be seen here.