cofactors

Examples of cofactors in the following topics:

• Phenylketonuria (PKU)

  • A rarer form of hyperphenylalaninemia occurs when PAH is normal, but there is a defect in the biosynthesis or recycling of the cofactor tetrahydrobiopterin (BH4) by the patient.
  • This cofactor is necessary for proper activity of the enzyme.
  • Dihydrobiopterin reductase activity is to replenish quinonoid-dihydrobiopterin back into its tetrahydrobiopterin form, which is an important cofactor in many metabolic reactions in amino acid metabolism.
  • Those with this deficiency may produce sufficient levels of PAH, but since tetrahydrobiopterin is a cofactor for PAH activity, deficient dihydrobiopterin reductase renders any PAH enzyme non-functional.
  • Tetrahydrobiopterin is also a cofactor in the production of L-DOPA from tyrosine and 5-hydroxy-l-tryptophan from tryptophan, which must also be supplemented as treatment in addition to the supplements for classical PKU.

• Role of Vitamin K

  • Coagulation is a complex cascade that requires many different cofactors and molecules to occur.
  • Vitamin K, calcium, and phospholipids are necessary cofactors for proper coagulation, and people deficient in these substances will be more susceptible to uncontrolled bleeding.
  • Calcium and phospholipids (a platelet membrane constituent) are required cofactors for prothrombin activation enzyme complexes to function.

• Measuring Blood Pressure

  • The guidelines for acceptable readings also take into account other cofactors for disease, such as pre-existing health factors.

• Blood Supply to the Liver

  • The liver also removes vitamins and cofactors from the blood for storage, as well as filters any toxins that may have been absorbed along with the food.

• Fibrinolysis

  • Warfarin inhibits vitamin K cofactor activation during the coagulation cascade, and citrates chelate calcium to prevent prothrombin activation into thrombin.