Protein of the Week: ribonuclease inhibitor
Ribonuclease inhibitor (PDB code 2BNH, structure generated with PyMOL) binds to the potent enzyme ribonuclease at its active site. Its structure consists of alternating α-helices (in red) and parallel β-strands (in gold) combined in a crescent shape that clamps to its target.
RNAse catalyzes the hydrolysis of phosphodiester bonds in ribonucleic acid polymers (RNA); part of the mechanism (minus the general base removal of a proton) in which the 2' hydroxyl group attacks the phosphoryl group is shown below. Deoxyribonucleic acid (DNA) lacks this 2' hydroxyl, giving it enhanced stability relative to RNA and making it suitable for long term information storage.
In the picture below, ribonuclease (in the center) is shown bound to ribonuclease inhibitor (PDB 1DFJ)