Biosynthesis Blood coagulation

The presence of Calcium (Ca ) is necessary for blood coagulation and subsequently prevents hemorrhaging from tissue injuries. The mechanism consists of cascade-type process in which stages are connected with the presence of Ca. Many of the so-called factors of blood coagulation are well known. Vitamin K is necessary in the biosynthesis of the factors IX, X, and VII and of prothrombin. The 1,25-dioxiform of vitamin D3 facilitates the process of Ca reception from the intestines. Accumulation of Ca and its release from humans is a complex system, and also includes vitamin D. 

Cation-JT interactions are also prominent at the active sites of enzymes involving cationic substrates. Key examples include the blood coagulation serine proteases Factor Xa and thrombin, and a number of enzymes that use S-adenosyhnethionine. a sulfonium ion that serves as nature s ubiquitous methyl transfer agent. A spectacular series of examples is the array of enzymes that catalyze the cationic cyclizations of polyenes in a key step of terpene and steroid biosynthesis. It is now clear that... 

Compounds with vitamin K activity (Table 6.2) are required in our diets for y-carboxyglutamate biosynthesis (Table 4.1). This amino acid is produced from certain protein glutamyl residues by carboxylation. Proteins that contain y-carboxyglutamate are blood prothrombin and coagulation factors VII, IX, and X (see Chapter 7). Other proteins of this type are osteocalcin from bone and several kidney and muscle calcium-binding proteins. 

Extensive investigations on the biosynthesis of fructose from blood glucose in seminal vesicle epithelium from several species and rat coagulating gland have suggested that three enzymatic pathways are... 

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