Figure 1. Chemical Structure of BTZ.

Bortezomib (BTZ, Trade name Velcade®) is a dipeptide boronic acid which forms non-covalent bonds with the N-terminal hydroxyl groups of threonine residues of the 20S proteasome via the Boron atom’ activity as an electron receiver, thus forming stable tetrahedral intermediates which inhibit the catalytic activity of specific β-subunits (β5 mainly, and β1) resulting in inhibition of chymotrypsin-like and PGPH-like activities.