Figure 3.

Complex formed between epoxyketone pharmacophore of carfilzomib and the catalytic threonine of β5 subunit of proteasome (79); (A) Morpholino ring which is a six membered ring formed by bonding of Thr1Oγ nucleophile of β5 subunit with α carbon of the epoxyketone pharmacophore, proposed by Groll et al. (77); (B) 1, 4- oxazepano adduct which is a seven membered ring formed by bonding of Thr1Oγ nucleophile of β5 subunit with β carbon of the epoxyketone pharmacophore proposed by Schrader et al. (78).