Catalytic site‐specific inhibition of the 20S proteasome by 4‐hydroxynonenal

Abstract

The proteasome is responsible for most intracellular protein degradation and is essential for cell survival. Previous research has shown that the proteasome can be inhibited by a number of oxidants, including 4-hydroxynonenal (HNE). The present study demonstrates that HNE rapidly inhibits the chymotrypsin-like activity of the 20S proteasome purified from liver. Subunits containing HNE-adducts were identified following 2D gel electrophoresis, Western immunoblotting, and analysis by MALDI-TOF MS. At a time when only the chymotrypsin-like activity was inhibited, the α6/C2 subunit was uniquely modified. These results provide important molecular details regarding the catalytic site-specific inhibition of proteasome by HNE.