We all might have experienced a small incision in our fingers during cutting/slicing vegetables. Though it is not very painful, loss of some blood is inevitable. Fortunately, the bleeding stops quickly. The platelets in the blood is doing this trick; by sticking together, they form clots and stops further loss of blood from the wound site. Researchers at Department of Chemistry and Emory’s School of Medicine, Emory University, USA, lead by Prof. Khalid Salaita have successfully identified the key molecular forces responsible to activate blood clotting for the first time. Their findings are published in the Proceedings of the National Academy of Sciences and in Nature Methods.
Fibrinogen (third most abundant protein in blood) acts like a glue and stick the platelets together during clotting. In spite of the presence of ~70,000 copies of receptors on the surface of each platelet to latch on with the fibrinogen, the platelets will not perform this action under normal conditions (any abnormal clotting would lead to strokes). The platelets will be in flow until we experience an injury wherein the receptors of platelets rapid bind with the fibrinogen, resulting in agglomeration of platelets followed by clotting.
Anchoring fibrinogen ligands on the surface of a lipid membrane has enabled them to slip and slide laterally, but resisted their movement perpendicular to the surface. When platelets are introduced to this surface, they failed to activate and stick together. On the contrary, when the fibrinogen ligands are anchored on a glass slide, they are unable to move laterally and under such conditions, the platelets are rapidly activated. To activate clotting, the blood platelets require a targeted force of the order of 5-20 piconewtons. When the platelets starts to stick with each other to form a clot they contract toward a line, or central axis, in each cell. However, they are not pulled together toward a shared central axis, rather they are pulled in such a way to form clusters with a random orientation.
T.S.N. Sankara Narayanan
Recent Advancements in Science 