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The most obvious, first effects (gingival and hair problems) of absence of ascorbic acid in humans come from the resulting defect in hydroxylation of proline residues of collagen, with reduced stability of the collagen molecule, causing scurvy. Increased serum and urine levels of hydroxyproline have also been demonstrated in Paget's disease. [10]
Prolyl 4-hydroxylase subunit alpha-1 is an enzyme that in humans is encoded by the P4HA1 gene. [5] [6] This gene encodes a component of prolyl 4-hydroxylase, a key enzyme in collagen synthesis composed of two identical alpha subunits and two beta subunits. The encoded protein is one of several different types of alpha subunits and provides the ...
Procollagen-proline dioxygenase catalyzes the following reaction: L-proline + alpha-ketoglutaric acid + O 2 → (2S, 4R)-4-hydroxyproline + succinate + CO 2. The mechanism for the reaction is similar to that of other dioxygenases, and occurs in two distinct stages: [3] In the first, a highly reactive Fe(IV)=O species is produced.
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.
Proline and its higher homolog pipecolic acid affect the secondary structure of protein. D-alpha-amino acid - L-alpha-amino acid sequence can induce beta hairpin. [1] It suggested that acyclic secondary amino acids are more flexible than cyclic secondary amino acids in protein by replacement of pipecolic acid by N-methyl-L-alanine in efrapeptin C.
In enzymology, a 4-hydroxyproline epimerase (EC 5.1.1.8) is an enzyme that catalyzes the chemical reaction trans -4-hydroxy-L-proline ⇌ {\displaystyle \rightleftharpoons } cis -4-hydroxy-D-proline Hence, this enzyme has one substrate , trans-4-hydroxy-L-proline , and one product , cis-4-hydroxy-D-proline .
The following other wikis use this file: Usage on ar.wikipedia.org حمض أميني غير مولد للبروتين; Usage on azb.wikipedia.org
proline. Secondary amino acids, amino acids containing a secondary amine group are sometimes named imino acids, [2] [3] though this usage is obsolescent. [1] The only proteinogenic amino acid of this type is proline, although the related non-proteinogenic amino acids hydroxyproline [4] [5] [6] and pipecolic acid [7] have often been included in studies of this class of compounds.