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Hydroxylation

 

 
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Hydroxylation
 
 
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Hydroxylation is any chemical
Chemistry

Chemistry is the science concerned with the composition, structure, and properties of matter, as well as the changes it undergoes during chemical reactions....
 process that introduces one or more hydroxyl groups (-OH) into a compound (or radical) thereby oxidizing it. In biochemistry
Biochemistry

Biochemistry is the study of the chemistry processes in living organisms. It deals with the structure and function of cellular components such as proteins, carbohydrates, lipids, nucleic acids and other biomolecules....
, hydroxylation reactions are often facilitated by enzyme
Enzyme

Enzymes are biomolecules that catalysis chemical reactions. Almost all enzymes are proteins. In enzymatic reactions, the molecules at the beginning of the process are called Substrate , and the enzyme converts them into different molecules, the products....
s called hydroxylases.

Hydroxylation in proteins
The principal residue to be hydroxylated in protein
Protein

Proteins are organic compounds made of amino acids arranged in a linear chain and joined together by peptide bonds between the carboxyl and amino groups of adjacent amino acid Residue ....
s is proline
Proline

Proline is an a-amino acid, one of the twenty DNA-encoded amino acids. Its codons are CCU, CCC, CCA, and CCG. It is not an essential amino acid, which means that humans can synthesize it....
. The hydroxilation occurs at the atom, forming hydroxyproline
Hydroxyproline

4-Hydroxyproline, or hydroxyproline , is an uncommon amino acid, abbreviated as HYP, e.g., in Protein Data Bank....
 (Hyp), an essential element of collagen
Collagen

Collagen is the main protein of connective tissue in animals and the most abundant protein in mammals, making up about 25% to 35% of the whole-body protein content....
, in turn a necessary element of connective tissue
Connective tissue

Connective tissue is a form of fibrous biological tissue.It is one of the four types of tissue in traditional classifications .Collagen is the main protein of connective tissue in animals and the most abundant protein in mammals, making up about 25% of the total protein content....
.






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Encyclopedia


Hydroxylation is any chemical
Chemistry

Chemistry is the science concerned with the composition, structure, and properties of matter, as well as the changes it undergoes during chemical reactions....
 process that introduces one or more hydroxyl groups (-OH) into a compound (or radical) thereby oxidizing it. In biochemistry
Biochemistry

Biochemistry is the study of the chemistry processes in living organisms. It deals with the structure and function of cellular components such as proteins, carbohydrates, lipids, nucleic acids and other biomolecules....
, hydroxylation reactions are often facilitated by enzyme
Enzyme

Enzymes are biomolecules that catalysis chemical reactions. Almost all enzymes are proteins. In enzymatic reactions, the molecules at the beginning of the process are called Substrate , and the enzyme converts them into different molecules, the products....
s called hydroxylases.

Hydroxylation in proteins


The principal residue to be hydroxylated in protein
Protein

Proteins are organic compounds made of amino acids arranged in a linear chain and joined together by peptide bonds between the carboxyl and amino groups of adjacent amino acid Residue ....
s is proline
Proline

Proline is an a-amino acid, one of the twenty DNA-encoded amino acids. Its codons are CCU, CCC, CCA, and CCG. It is not an essential amino acid, which means that humans can synthesize it....
. The hydroxilation occurs at the atom, forming hydroxyproline
Hydroxyproline

4-Hydroxyproline, or hydroxyproline , is an uncommon amino acid, abbreviated as HYP, e.g., in Protein Data Bank....
 (Hyp), an essential element of collagen
Collagen

Collagen is the main protein of connective tissue in animals and the most abundant protein in mammals, making up about 25% to 35% of the whole-body protein content....
, in turn a necessary element of connective tissue
Connective tissue

Connective tissue is a form of fibrous biological tissue.It is one of the four types of tissue in traditional classifications .Collagen is the main protein of connective tissue in animals and the most abundant protein in mammals, making up about 25% of the total protein content....
. Proline hydroxylation is also a vital component of hypoxia
Hypoxia (medical)

Hypoxia is a Pathology condition in which the body as a whole or a region of the body is deprived of adequate oxygen supply. Variations in arterial oxygen concentrations can be part of the normal physiology, for example, during strenuous physical exercise....
 response via hypoxia inducible factors. In some cases, proline may be hydroxylated instead on its atom. Lysine may also be hydroxylated on its atom, forming hydroxylysine
Hydroxylysine

5-Hydroxylysine is an amino acid with the molecular formula C6H14N2O3. It is a hydroxy derivative of lysine....
 (Hyl).

These three reactions are catalyzed by very large, multi-subunit enzymes prolyl 4-hydroxylase, prolyl 3-hydroxylase and lysyl 5-hydroxylase, respectively. These reactions require iron (as well as molecular oxygen and a-ketoglutarate) to carry out the oxidation, and use ascorbic acid
Ascorbic acid

Ascorbic acid is a sugar acid with antioxidant properties. Its appearance is white to light-yellow crystals or powder. It is water-soluble. The L-enantiomer of ascorbic acid is commonly known as vitamin C....
 (vitamin C) to return the iron to its oxidized state. Deprivation of ascorbate leads to deficiencies in proline hydroxylation, which leads to less stable collagen, which can manifest itself as the disease scurvy
Scurvy

Scurvy is a disease resulting from a deficiency of vitamin C, which is required for the synthesis of collagen in humans. The chemical name for vitamin C, ascorbic acid, is derived from the Latin name of scurvy, scorbutus....
. Since citrus fruits are rich in vitamin C, British sailor
Sailor

A sailor or mariner is a person who navigates ships or assists in their operation, maintenance, or service. The term can apply to professional mariners, military personnel, and recreational sailors as well as a plethora of other uses....
s were given limes
Lime (fruit)

Lime is a term referring to a number of different fruits , both species and Hybrid , which are typically round, green to yellow in color, 3?6 cm in diameter, generally containing sour pulp, and frequently associated with the lemon....
 to combat scurvy on long ocean voyages; hence, they were called "lymies".

Examples of hydroxylases

  • 17a-hydroxylase
  • Cholesterol 7 alpha-hydroxylase
    Cholesterol 7 alpha-hydroxylase

    Cholesterol 7 alpha-hydroxylase , the rate-limiting enzyme in the synthesis of bile acid from cholesterol, catalyzing the formation of 7-alpha-hydroxycholesterol....
  • Phenylalanine hydroxylase
    Phenylalanine hydroxylase

    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 phenylalanine, such that it becomes tyrosine:...
  • Tyrosine hydroxylase
    Tyrosine hydroxylase

    Tyrosine hydroxylase or tyrosine 3-monooxygenase is the enzyme responsible for catalyzing the conversion of the amino acid L-tyrosine to dihydroxyphenylalanine ....