Question

Hirudin gene inserted in Brassica napus was
A) Synthesised chemically
B) Obtained from leech
C) Got from Bacillus thuringiensis
D) Brassica campestris

Answer 1

Hint: Hirudin is a peptide naturally occurring in the salivary glands of blood-sucking leeches (such as Hirudo medicinalis) that has a blood anticoagulant property. Brassica napus, commonly called rapeseed, is a bright-yellow flowering member of the mustard or cabbage family, cultivated mainly for its oil-rich seed, containing appreciable amounts of erucic acid.

Complete Answer:
A key event in the process of blood coagulation is the conversion of fibrinogen into fibrin by the protease enzyme thrombin. Fibrin is then cross linked by the factor XIII (called Fibrin Stabilizing Factor) to form a blood clot. The principal inhibitor of thrombin in normal blood circulation is antithrombin. Hirudin is similar to antithrombin, based on its ability to inhibit the procoagulant activity of thrombin. Unlike heparin, hirudin acts directly on thrombin, rather than acting through other clotting factors. Extraction of hirudin from natural sources is difficult since only a meagre amount of the peptide can only be obtained, so a method for producing and purifying hirudin using recombinant biotechnology has been developed. This has led to the development of a number of hirudin-based anticoagulant pharmaceutical products in the market.

Hence, the gene inserted in Brassica napus was synthesized chemically using recombinant technology.

Note:
Full length hirudin is made up of 65 amino acids which are organized into a compact N-terminal domain containing three disulfide bonds and a C-terminal domain. The C-terminal domain makes numerous electrostatic interactions with the anion-binding exosite of thrombin, while the last five residues are arranged in a helical loop, forming many hydrophobic contacts. Natural hirudin will contain a mixture of various isoforms of the protein.