Novel Furin Inhibitors with Potent Anti‐infectious Activity

Abstract

New peptidomimetic furin inhibitors with unnatural amino acid residues in the P3 position were synthesized. The most potent compound 4-guanidinomethyl-phenylacteyl-Arg-Tle-Arg-4-amidinobenzylamide (MI-1148) inhibits furin with a Ki value of 5.5 pM. The derivatives also strongly inhibit PC1/3, whereas PC2 is less affected. Selected inhibitors were tested in cell culture for antibacterial and antiviral activity against infectious agents known to be dependent on furin activity. A significant protective effect against anthrax and diphtheria toxin was observed in the presence of the furin inhibitors. Furthermore, the spread of the highly pathogenic H5N1 and H7N1 avian influenza viruses and propagation of canine distemper virus was strongly inhibited. Inhibitor MI-1148 was crystallized in complex with human furin. Its N-terminal guanidinomethyl group in the para position of the P5 phenyl ring occupies the same position as that found previously for a structurally related inhibitor containing this substitution in the meta position, thereby maintaining all of the important P5 interactions. Our results confirm that the inhibition of furin is a promising strategy for a short-term treatment of acute infectious diseases.

Structure of the unliganded form of the proprotein convertase furin suggests activation by a substrate-induced mechanism

“…Prompted by these observations, we reanalyzed the melting temperatures (T m ) of furin-inhibitor complexes and their dependence on the K i -values (6). In a semi-logarithmic representation of the data, an apparent linear relationship between pK i (range 6.4-11.3) and T m can be found.…”

“…The PCs are also involved in a large number of pathologies, including bacterial and viral infections, as well as cancer and metastasis. Therefore, these enzymes are intensely investigated as drug targets (3), using for example, peptide-derived compounds (4)(5)(6)(7)(8)(9), nonpeptidic small molecule compounds (10,11), and protein-based inhibitors (12)(13)(14)(15).…”

“…Different crystal structures of the inhibitor-bound murine (16) and human (6,17) enzyme, together with structural studies of the yeast homolog Kex2p (18,19) and modeling approaches (9, 20), gave hints of how substrates and substrate-derived inhibitors bind with high specificity to furin and to the PCs, but suffer from the lack of structural information of the unliganded enzyme. The commonly accepted notion is that the PCs bind their cognate substrates via recognition at several subsites, typically involving multiple tight contacts and hydrogen bonds.…”

Furin as proprotein convertase and its role in normal and pathological biological processes

“…На основе эглина созданы ингибиторы для фурина различной эффективности (K i от 1,6 нМ до 330 пМ). Ряд ингибиторов ПК пептидной природы созданы на основе белков и пептидов: С-концевой фрагмент белкового ингибитора ПК про7В2 (K i от мкМ до нМ); С-концевой фрагмент белкового ингибитора ПК -проSAAS (K i от мкМ до нМ); полипептиды, производные пропептидов ПК (K i в пределах нМ); циклические пептиды и псевдопептиды (K i в пределах от мкМ до нМ); пептидные хлорметилкетоны (K i = 3,4 нМ); полиаргинин содержащие пептиды (от 4 до 10 остатков Arg, K i = 40-74мкМ), которые обладают антибактериальным, антивирусным и антиканцерогенным действием [22][23][24], и др.…”

“…Однако внедрённых в клиническую практику препаратов не существует. Наиболее продвинутыми в контексте клинического применения являются исследования по использованию ингибиторов фурина и других ПК против бактериальных и вирусных инфекций, а также при онкологических заболеваниях [15,22,23]. Основные трудности по внедрению ингибиторов ПК в клинику связаны с их проницаемостью в клетки, так как многие исследования проведены на растворимой форме фурина, а также с недостаточными данными по профилю токсичности ингибиторов, возможными последствиями их действия для здоровья, влиянием на иммунную толерантность и выявленной летальностью эмбрионов у мышей [16,23,25].…”