vitamin K catabolic process

Definition

Target type: biologicalprocess

The chemical reactions and pathways resulting in the breakdown of any of the forms of vitamin K, quinone-derived vitamins which are involved in the synthesis of blood-clotting factors in mammals. [GOC:jl, http://www.dentistry.leeds.ac.uk/biochem/thcme/vitamins.html#k]

The catabolism of vitamin K, a fat-soluble vitamin essential for blood clotting and bone health, is a complex process involving multiple enzymes and cellular pathways. The primary site of vitamin K metabolism is the liver.

First, vitamin K is absorbed from the diet or supplements and transported to the liver bound to lipoproteins. In the liver, vitamin K undergoes a series of enzymatic reactions. The initial step is the reduction of vitamin K epoxide (K1-2,3-epoxide) to vitamin K hydroquinone (K1-H2) by the enzyme vitamin K epoxide reductase (VKOR). This reaction is essential for the activation of vitamin K and is the target of the anticoagulant drugs warfarin and dicoumarol.

Activated vitamin K (K1-H2) participates in the γ-carboxylation of specific glutamate residues in proteins involved in blood clotting, bone metabolism, and other physiological processes. This carboxylation reaction requires a carboxylase enzyme complex, which includes a vitamin K-dependent carboxylase (GGCX) and a reductase component.

After participating in the carboxylation reaction, vitamin K is oxidized to vitamin K epoxide (K1-2,3-epoxide). The vitamin K epoxide is then reduced back to vitamin K hydroquinone (K1-H2) by VKOR, completing the cycle.

The catabolism of vitamin K also involves various other metabolic pathways. Some of the metabolic products, such as the 2,3-epoxide and the 2,3-diol, are excreted in the urine. The catabolism of vitamin K is influenced by several factors, including age, dietary intake, and liver function. Deficiencies in vitamin K can lead to various health problems, including bleeding disorders, osteoporosis, and bone fractures.

The catabolic process of vitamin K is tightly regulated to ensure that sufficient levels of the vitamin are available for its various physiological functions. This regulation is achieved through feedback mechanisms, which ensure that the synthesis of vitamin K-dependent proteins is balanced with the availability of vitamin K.'
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Proteins (1)

Compounds (6)