A cofactor is a chemical substance, which binds to a protein, and which is necessary for the biological activity of the latter. These proteins are often enzymes, and cofactors can be thought of as "helper molecules" aiding in biochemical transformations. Factor V (FV) is a protein mainly synthesized by the liver. It is the enzymatic cofactor of FX and is activated in FVa by thrombin and / or FXa. It forms with FXa a complex which, in the presence of phospholipids and calcium, activates prothrombin to thrombin. The FVa is neutralized by the PCa.
All proteins are accompanied by product information sheets which describe proper storage conditions. Many of our preparations are formulated in 50 % (vol/vol) glycerol/H₂O which will remain in fluid phase during storage at -20° C. This preferred method of storage yields the greatest stability while still allowing access to the stock sample without repeated thawing and freezing steps. All products which are formulated with glycerol/H₂O should be stored at -20° C. Temperatures lower than -30° C should be avoided in order to prevent a phase transition. When preparing to make a dilution of the stock sample, remove the sample from storage at -20° C and place on ice for a brief period of time (5-10 min). The sample will become less viscous and thus easier to pipe. Never allow protein solutions to remain at room temperature for excessive periods of time.
The lyophilized presentation allows stability until the expiration date.