ω-oxidation of fatty acid carbon chains that degrades the acids, with the preferred pathway being the β-oxidation in the mitochondria and peroxisomes. Very long chain fatty acids cannot be β-oxidized. The number of carbon atoms in the chains of such acids exceeds 22. Such chains must be shortened before being oxidized by mitochondria. The CYP4F2 enzyme is involved in catalyzing the ω-oxidation and chain shortening of such acids. Metabolism of vitamins The enzyme plays an important role in vitamin metabolism by chain shortening. CYP4F2 is the only known enzyme to ω-hydroxylate tocotrienols and tocopherols (types of Vitamin E), thus making it a key regulator of circulating plasma Vitamin E levels. It catalyzes ω-hydroxylation of the phytyl chain of tocopherols (forms of vitamin E), with preference for gamma-tocopherols over α-tocopherols, thus promoting retention of α-tocopherols in tissues. Both types of Vitamin K (K1 and K2) can be used as co-factors for γ-glutamyl carboxylase, an enzyme that catalyzes the posttranslational modification of Vitamin K-dependent proteins, thus biochemically activating the proteins involved in blood coagulation and bone mineralization. CYP4F2 ω-xydroxylates and inactivates Vitamin K. As a result, CYP4F2 becomes vital negative regulator of circulating Vitamin K levels. Production of 20-HETE CYP4F2 along with CYP4A22, CYP4A11, CYP4F3 and CYP2U1 also metabolize arachidonic acid to 20-Hydroxyeicosatetraenoic acid (20-HETE) by an ω-oxidation reaction, with the predominant 20-HETE-synthesizing enzymes in humans being CYP4F2, followed by CYP4A11. 20-HETE regulates blood flow, vascularization, blood pressure, and kidney tubule absorption of ions in rodents and possibly humans. The CYP4F2*3 (rs2108622) polymorphism (the enzyme protein with valine residue replaced to methionine residue at position 433) leads to reduced capacity to metabolize arachidonic acid to 20-HETE, but increased urinary excretion of 20-HETE. Researchers have identified at least 3 more single-nucleotide polymorphisms (2024C>G P85A; 80C>T A27V rs771576634; 139C>T R47C rs115517770) which may affect conversion of arachidonic acid to HETE-20. Metabolism of fatty acids Members of the CYP4A and CYP4F sub-families may also ω-hydroxylate and thereby reduce the activity of various fatty acid metabolites of arachidonic acid including leukotriene B4, 5-HETE, 5-oxo-eicosatetraenoic acid, 12-HETE, and several prostaglandins that are involved in regulating various inflammatory, vascular, and other responses in animals and humans. This hydroxylation-induced inactivation may underlie the proposed roles of the cytochromes in dampening inflammatory responses and the reported associations of certain CYP4F2 single-nucleotide polymorphisms (SNPs) with human Crohn's disease and Coeliac disease. Tye enzyme catalyzes ω-hydroxylation of 3-hydroxy fatty acids. It converts