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Hydroxyproline is a major component of the protein collagen, [3] comprising roughly 13.5% of mammalian collagen. Hydroxyproline and proline play key roles for collagen stability. [4] They permit the sharp twisting of the collagen helix. [5]
In 1954, Ramachandran & Kartha (13, 14) advanced a structure for the collagen triple helix on the basis of fiber diffraction data. It consists of a triple helix made of the repetitious amino acid sequence glycine-X-Y, where X and Y are frequently proline or hydroxyproline. [2] [3] Collagen folded into a triple helix is known as tropocollagen.
Due to the abundance of collagen (about one third of total protein) in humans, and the high occurrence of this modification in collagen, hydroxyproline is quantitatively the most abundant post-translational modification in humans. [14] The enzyme acts specifically on proline contained within the X-Pro-Gly motif – where Pro is proline.
1281 12825 Ensembl ENSG00000168542 ENSMUSG00000026043 UniProt P02461 P08121 RefSeq (mRNA) NM_000090 NM_001376916 NM_009930 RefSeq (protein) NP_000081 NP_034060 Location (UCSC) Chr 2: 188.97 – 189.01 Mb Chr 1: 45.35 – 45.39 Mb PubMed search Wikidata View/Edit Human View/Edit Mouse Type III Collagen is a homotrimer, or a protein composed of three identical peptide chains (monomers), each ...
Proline: P Pro Pro contains an unusual ring to the N-end amine group, which forces the CO-NH amide sequence into a fixed conformation. It can disrupt protein folding structures like α helix or β sheet, forcing the desired kink in the protein chain. Common in collagen, it often undergoes a post-translational modification to hydroxyproline ...
Furthermore, proline is rarely found in α and β structures as it would reduce the stability of such structures, because its side chain α-nitrogen can only form one nitrogen bond. Additionally, proline is the only amino acid that does not form a red-purple colour when developed by spraying with ninhydrin for uses in chromatography. Proline ...
The encoded protein is one of several different types of alpha subunits and provides the major part of the catalytic site of the active enzyme. In collagen and related proteins, prolyl 4-hydroxylase catalyzes the formation of 4-hydroxyproline that is essential to the proper three-dimensional folding of newly synthesized procollagen chains.
The most frequently hydroxylated amino acid residue in human proteins is proline. This is because collagen makes up about 25–35% of the protein in our bodies and contains a hydroxyproline at almost every 3rd residue in its amino acid sequence. Collagen consists of both 3‐hydroxyproline and 4‐hydroxyproline residues. [6]