Fibrinogen is a blood protein that is involved in clotting and is converted to fibrin by thrombin. Fibrinogen has an approximate molecular weight of 340 kDa. It consists of three non-identical pairs of disulfidebonded chains. The α-chain has an approximate molecular weight of 63,5 kDa, the β-chain 56 kDa, and the γ-chain 47 kDa. At the amino termini, the three chains are connected in a dimeric disulfide knot (DSK). A second DSK occurs later in the molecule. Fibrinogen has approximately 4% carbohydrate content.