Hydroxylation is any chemical process that introduces one or more hydroxyl groups (-OH) into a compound (or radical) thereby oxidizing it. Redox (shorthand for reduction-oxidation reaction describes all Chemical reactions in which atoms have their Oxidation number ( Oxidation state In biochemistry, hydroxylation reactions are often facilitated by enzymes called hydroxylases. Enzymes are Biomolecules that catalyze ( ie increase the rates of Chemical reactions Almost all enzymes are Proteins
Hydroxylation in proteins
The principal residue to be hydroxylated in proteins is Proline. Proline (abbreviated as Pro or P) is an α- Amino acid, one of the twenty DNA -encoded amino acids The hydroxilation occurs at the Cγ atom, forming hydroxyproline (Hyp), an essential element of collagen, in turn a necessary element of connective tissue. 4-Hydroxyproline, or hydroxyproline ( C 5 H 9 O 3 N) is an uncommon Amino acid, abbreviated as HYP Collagen is the main Protein of Connective tissue in Animals and the most abundant protein in Mammals making up about 50% of the whole-body protein Proline hydroxylation is also a vital component of hypoxia response via hypoxia inducible factors. Chronic Hypoxia is a pathological condition in which the body as a whole ( generalized hypoxia) or region of the body ( tissue hypoxia) is deprived of adequate Hypoxia-inducible factors (HIFs are Transcription factors that respond to changes in available Oxygen in the cellular environment in specific to decreases in oxygen In some cases, proline may be hydroxylated instead on its Cβ atom. Lysine may also be hydroxylated on its Cδ atom, forming hydroxylysine (Hyl). 5-Hydroxylysine is an Amino acid with the molecular formula C6H14N2O3
These three reactions are catalyzed by very large, multi-subunit enzymes prolyl 4-hydroxylase, prolyl 3-hydroxylase and lysyl 5-hydroxylase, respectively. Prolyl hydroxylase (or procollagen-proline dioxygenase) is an enzyme involved in the production of Collagen, acting to Hydroxylate Proline to Prolyl hydroxylase (or procollagen-proline dioxygenase) is an enzyme involved in the production of Collagen, acting to Hydroxylate Proline to Lysyl hydroxylase (or procollagen-lysine 5-dioxygenase) is an Oxygenase Enzyme which catalyzes the Hydroxylation of Lysine to These reactions require iron (as well as molecular oxygen and α-ketoglutarate) to carry out the oxidation, and use ascorbic acid (vitamin C) to return the iron to its oxidized state. This article deals with the molecular aspects of ascorbic acid Deprivation of ascorbate leads to deficiencies in proline hydroxylation, which leads to less stable collagen, which can manifest itself as the disease scurvy. Scurvy (NLat scorbutus is a disease resulting from a deficiency of Vitamin C, which is required for the synthesis of Collagen in humans Since citrus fruits are rich in vitamin C, British sailors were given limes to combat scurvy on long ocean voyages; hence, they were called "lymies". Lime is a term referring to a number of different fruits (generally Citruses, both Species and hybrids, which are typically round green to yellow
Examples of hydroxylases
CYP17A1 (also known as 17&alpha-hydroxylase/1720 lyase/1720 desmolase) is a Cytochrome P450 enzyme which acts upon Pregnenolone and Progesterone Cholesterol 7 alpha-hydroxylase (CYP7A1 the Rate-limiting enzyme in the synthesis of Bile acid from Cholesterol, catalyzing the formation of 7-alpha-hydroxycholesterol Phenylalanine hydroxylase ( is an Enzyme which catalyses the reaction causing the addition of an Hydroxyl group to the end of the 6-carbon aromatic ring of Tyrosine hydroxylase or tyrosine 3-monooxygenase is the Enzyme responsible for catalyzing the conversion of the Amino acid L-tyrosine toDapyx Software network: MP3 Explorer | Ebook Manager | Zenithic