C-Npys (S-3-nitro-2-pyridinesulfenyl) and peptide derivatives can inhibit a serine-thiol proteinase activity from Paracoccidioides brasiliensis

Abstract

The inhibitory capacity of C-Npys (S-[3-nitro-2-pyridinesulfenyl]) derivatives over thiolcontaining serine proteases has never been tested. In the present work we used an extracellular serine-thiol proteinase activity from the fungal pathogen Paracoccidioides brasiliensis (PbST) to describe a potent inhibitory capacity of Bzl-C(Npys)KRLTL-NH 2 and Bzl-MKRLTLC(Npys)-NH 2 . The assays were performed with PbST enriched upon affinity chromatography in a paminobenzamidine (pABA)-Sepharose column. Although PbST can cleave the fluorescence resonance energy transfer peptide Abz-MKRLTL-EDDnp between L-T, the C(Npys) derivatives were not substrates nor were they toxic in a cell detachment assay, allowing therapeutic use. The best inhibitor was Bzl-C(Npys)KRLTL-NH 2 (K i = 16 nM), suggesting that the peptide sequence promoted a favorable interaction, especially when C(Npys) was placed at a further position from the L-T bond, at the N-terminus. Inhibition was completely reverted with dithioerythritol, indicating that it was due to the reactivity of the C(Npys) moiety with a free SH-group.

The 3‐nitro‐2‐pyridinesulfenyl group: synthesis and applications to peptide chemistry

“…The inhibitory potency of the Npys derivative compared to the thiol‐containing serine proteases was demonstrated by Matsuo et al using the fungal pathogen Paracoccidioides brasiliensis . The protease activity was impaired by conjugation of a small Cys(Npys)‐containing hexapeptide . Matsueda's group also showed that the controlled introduction of Npys at selected peptides provided selective platelet calpain inhibitors that did not inhibit the functions of other proteins, such as thrombin, by selectively delivering the Npys group.…”