Question

Anticoagulant hirudin is found in
A. Scorpion
B. Snake
C. Leech
D. Lizard

Answer 1

Hint: Hirudin is a natural peptide found in the salivary glands of sanguivorous (blood-sucking) leeches like Hirudo medicinalis. It signifies a new anticoagulant agent in the medical field where heparin has been the only available drug for many years.

Complete answer:
Leeches secrete an enzyme in their saliva called hirudin. Hirudin is a strong anticoagulant. Leeches produce hirudin to prevent their host from forming a clot so that they can suck the blood more easily.
Hirudin is a peptide containing 65 amino acids with three disulfide bonds and is obtained from the saliva of the medicinal leech. It is the most potent natural inhibitor of both soluble and clot-bound thrombin. Hirudin combines with thrombin with high affinity and covers more than 20% of the surface area of thrombin. This coverage prevents thrombus growth and platelet activation. Hirudin is not metabolized in the human bloodstream and is excreted unchanged by kidney filtration. Nowadays, recombinant technology has developed various methods for the production of recombinant forms of hirudin (r-hirudin) in sufficient amounts for therapeutic purposes. Hirudin has been used in the treatment of various ailments such as deep vein thrombosis and for coronary angioplasty. A very effective cream made from hirudin is used to shrink hematomas caused by musculoskeletal injuries.

The other given options like scorpion, snake and lizard do not have anticoagulant hirudin. So, the correct answer is option C.

Note: Hirudin is known as the most potent natural inhibitor of thrombin. Unlike antithrombin, hirudin binds to and inhibits only the activated thrombin, with a specific activity on fibrinogen. Thus, hirudin prevents or dissolves the formation of clots and thrombosis and has a great therapeutic value in blood coagulation disorders.