Authors: Feng Li Irina Chvyrkova Simon Terzyan Nancy Wakeham Robert Turner Arun K Ghosh Xuejun C Zhang Jordan Tang
Publish Date: 2012/01/25
Volume: 94, Issue: 4, Pages: 1041-1049
Abstract
The metalloprotease activity of lethal factor LF from Bacillus anthracis B anthracis is a main source of toxicity in the lethality of anthrax infection Thus the understanding of the enzymatic activity and inhibition of B anthracis LF is of scientific and clinical interests We have designed synthesized and studied a peptide inhibitor of LF R9LF1 with the structure NH2–dArg9–Val–Leu–Arg–CO–NHOH in which the Cterminal hydroxamic acid is commonly used in the inhibitors of metalloproteases to chelate the activesite zinc This inhibitor was shown to be very stable in solution and effectively inhibited LF in kinetic assays However its protection on murine macrophages against lethal toxin’s lysis activity was relatively weak in longer assays We further observed that the hydroxamic acid group in R9LF1 was hydrolyzed by LF and the hydrolytic product of this inhibitor is considerably weaker in inhibition of potency To resist this unique hydrolytic activity of LF we further designed a new inhibitor R9LF2 which contained the same structure as R9LF1 except replacing the hydroxamic acid group with NOdimethyl hydroxamic acid DMHA –NCH3–O–CH3 R9LF2 was not hydrolyzed by LF in longterm incubation It has a high inhibitory potency vs LF with an inhibition constant of 64 nM had a better protection of macrophages against LF toxicity than R9LF1 These results suggest that in the development of new LF inhibitors the stability of the chelating group should be carefully examined and that DMHA is a potentially useful moiety to be used in new LF inhibitors
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