Vitamin K

VITAMIN K 
 Vitamin K belongs to a group of chemical compounds called quinones. Two naturally-occurring form exist: Phylloquinone or vitamin K1 (in plant foods) and Menaquinone or vitamin K2 (in animal tissues and synthesised by bacteria in the large intestine). Menadione is a synthetic form of vitamin K used previously as a therapeutic agent. Absorption and transportation Vitamin K digestion requires bile and pancreatic juice. It is absorbed from the small intestine into the lymphatic system after incorporation into chylomicrons and transported to the liver. Factors affecting absorption of fats also affect vitamin K absorption.

 Roles
1. Vitamin K acts to stimulate the synthesis of prothrombin and other blood-clotting factors needed to produce fibrin (a blood clot), the chemical substance that stops bleeding. Vitamin K also catalyses the conversion of the precursor of prothrombin to thrombin.
 2. A co-factor in href="http://www.chempapy.blogspot.com/" target="_blank">vitamin K-dependent carboxylation of precursor proteins (e.g. gammacarboxyglutamic acid). In the absence of vitamin K, carboxylation of precursor proteins in incomplete and proteins are secreted in plasma in various uncarboxylated forms which lack biological activity.
Vitamin K is also a co-factor in vitamin K-dependent proteins (blood coagulation proteins, bone proteins, osteocalcin)   Dietary sources Green leafy vegetables, broccoli, Brussels sprouts, swiss chard, kale, spinach, cabbage, plant oils (e.g. soybean, canola, olive). Deficiency Prolonged bleeding is a well-known vitamin K deficiency. It increases risk of bleeding in the first week of life. Newborns are more at risk due to poor or little placental transfer of vitamin K during pregnancy, low concentration of plasma clotting factors due to hepatic immaturity, low vitamin K content of breast milk, sterile nature of their intestines to produce bacterial vitamin K.