Mechanism of time-dependent inhibition of polypeptide deformylase by actinonin |
| |
Authors: | Van Aller Glenn S Nandigama Ravi Petit Chantal M DeWolf Walt E Quinn Chad J Aubart Kelly M Zalacain Magdalena Christensen Siegfried B Copeland Robert A Lai Zhihong |
| |
Affiliation: | Enzymology and Mechanistic Pharmacology, GlaxoSmithKline, 1250 South Collegeville Road, Collegeville, Pennsylvania 19426, USA. |
| |
Abstract: | Polypeptide deformylase (PDF) is an essential bacterial metalloenzyme responsible for the removal of the N-formyl group from the N-terminal methionine of nascent polypeptides. Inhibition of bacterial PDF enzymes by actinonin, a naturally occurring antibacterial agent, has been characterized using steady-state and transient kinetic methods. Slow binding of actinonin to these enzymes is observed under steady-state conditions. Progress curve analysis is consistent with a two-step binding mechanism, in which tightening of the initial encounter complex (EI) results in a final complex (EI*) with an extremely slow, but observable, off-rate (t(1/2) for inhibitor dissociation >or=0.77 days). Stopped-flow measurement of PDF fluorescence confirms formation of EI and provides a direct measurement of the association rate. Rapid dilution studies establish that the potency of actinonin is enhanced by more than 2000-fold upon tightening of EI to form EI*, from K(i) = 530 nM (EI) to Ki*
|
| |
Keywords: | |
本文献已被 PubMed 等数据库收录! |
|