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Hydroxyproline is found in few proteins other than collagen. For this reason, hydroxyproline content has been used as an indicator to determine collagen and/or gelatin amount. However, the mammalian proteins elastin and argonaute 2 have collagen-like domains in which hydroxyproline is formed.
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.
In 2001, biologically active hydroxyproline-rich glycopeptides were isolated from tobacco which activated the production of protease inhibitors in a similar way to systemin in tomatoes. [1] Although they are structurally unrelated to systemins, their similar function resulted in them being named hydroxyproline-rich systemins (HypSys).
One process is a one-step mechanism in which proteins from the cytoplasm of bacteria are transported and delivered directly through the cell membrane into the host cell. Another involves a two-step activity in which the proteins are first transported out of the inner cell membrane, then deposited in the periplasm , and finally through the outer ...
Hence, the hydroxylation of proline is a critical biochemical process for maintaining the connective tissue of higher organisms. Severe diseases such as scurvy can result from defects in this hydroxylation, e.g., mutations in the enzyme prolyl hydroxylase or lack of the necessary ascorbate (vitamin C) cofactor.
Procollagen-proline dioxygenase, commonly known as prolyl hydroxylase, is a member of the class of enzymes known as alpha-ketoglutarate-dependent hydroxylases.These enzymes catalyze the incorporation of oxygen into organic substrates through a mechanism that requires alpha-Ketoglutaric acid, Fe 2+, and ascorbate.
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 structure of the Bacterial Microcompartment shell. The first structure of a BMC shell, determined by X-ray crystallography and cryo-electron microscopy, [1] contains representatives of each of the shell protein types: BMC-P, BMC-H and BMC-T, in both its trimer (upper right) and dimer of trimer (lower right), forms.