Vitamin K: its structure, synthesis, role in biological processes and sources

Vitamin K: its structure, synthesis, role in biological processes and sources

 Vitamin K is a fat-soluble vitamin that belongs to a family of 2- methyl 1, 4 naphthoquinone and its derivative. Naturally occurring  Vitamin K has two subfamilies K1 and K2. Vitamin K is a factor in blood coagulation (koagulation -Danish). Vitamin K1 is also known as Phylloquinone

Vitamin K-2 Menaquinone family and named as  MK 1- MK 14 on the basis of the length of the isoprene chain.The isoperene may consists of alkane or alkyne R group i.e. saturated or unsaturated with tail length 1-14 methy group. K-3 is synthetic vitamin K known as menadione.

SYNTHESIS OF VITAMIN K

 Vitamin K1 is also known as Phylloquinone. It is naturally synthesized in plant green leaves.  It is mainly associated with the chloroplast of the plant cells and directly involved in photosynthesis.

 The other class of Vitamin K is vitamin K2 which is known as menaquinone. It is naturally produced by bacteria that are present in the gut of animals.

 Vitamin K-1 is naturally synthesized in plants. Leafy vegetables are a good source of vitamin K-1. Its digestion is similar to fat digestion, thus  it is converted in micells similar to fat molecules and absorbed endothelial cells large intestine. Vitamin K 2 is naturally produced by gut bacteria.

ROLE OF VITAMIN K

Vitamin K is used as a cofactor by vitamin K-dependent gamma-glutamate carboxylase. Vitamin K-1 is converted to vitamin K-2 in the liver and stored in the pancreas, soft tissue, muscles, and kidney. It is transported through the lymphatic system. It is released where it is required.  Phylloquinone is the inactive form of Vitamin K. Which is converted into an active form.

The process involves NADPH-dependent K reductase or vitamin K quinone reductase that converts QUINONE into QUINOL the active form of Vitamin K.quinol is used in carboxylation reaction and as a result of which it is oxidized to vitamin K 2,3- epoxide, that in turn reduced to a quinone.

 Active vitamin K is used by carboxylase enzymes for carboxylation of gla- protein. This carboxylation is done at the glutamic acid of the Gla-domain to produce Gamma glutamate. Gamma glutamate can bind with calcium ions and form calcium chelates. This binding results in  the proper folding of these proteins

 Gla protein present in human fall in the category of several categories such as

 Coagulation factors such as  prothrombin, factor VII, IX, X

Anticoagulating proteins S, C, Z

 Matrix gla-protein.

 Osteocalcin is also a gla protein that requires Vitamin K for its binding with calcium,  required for the proper mineralization of bones.

 

Thus vitamin K has found its role in blood coagulation

 The proper formation of soft tissue(cartilage)

 Bone mineralization etc.

 Sources of Vitamin K

 Green leafy vegetables.

Fermented food eg; cheese

 Dairy products

 Whole grain

Healthy oil

A good amount of vitamin K is found in green leaves instead of animal sources. Fermented foods have better availability of vitamin K.

DEFICIENCY OF VITAMIN K
WHAT HINDER THE PROPER FUNCTIONING OF VITAMIN K

Antibiotics, as they kill gut microflora

Anticoagulants like warfarin, are antagonistic to vitamin K

Alcohol consumption

What should be done

Keep your gut healthy.  

Avoid alcohol 

Reduce intake of beverages

Eat salad

 An adult person requires 30-80 micrograms of Vitamin K in a daily diet. Further in adults, no poisoning for excess of Vitamin K has been observed.

 Infants may have low vitamin K as it cannot cross the placenta.

 Breastfeed have a low amount of Vitamin K so infants are required to be injected with Vitamin K to protect them from fatal brain injury.

The deficiency of vitamin K results in hemorrhage.

Excessive bleeding.

Osteoporosis i.e. weak bones

Improper formation of soft tissue.

Beverages that have added sugar and sodium

Consume healthy oils 

Infants should be given Vitamin K injection.