The Catalytic Mechanism of Human Parainfluenza Virus Type 3 Haemagglutinin‐Neuraminidase Revealed

Abstract

Human parainfluenza virus type 3 (hPIV-3) is one of the leading causes for lower respiratory tract disease in children, with neither an approved antiviral drug nor vaccine available to date. Understanding the catalytic mechanism of human parainfluenza virus haemagglutinin-neuraminidase (HN) protein is key to the design of specific inhibitors against this virus. Herein, we used (1) H NMR spectroscopy, X-ray crystallography, and virological assays to study the catalytic mechanism of the HN enzyme activity and have identified the conserved Tyr530 as a key amino acid involved in catalysis. A novel 2,3-difluorosialic acid derivative showed prolonged enzyme inhibition and was found to react and form a covalent bond with Tyr530. Furthermore, the novel derivative exhibited enhanced potency in virus blockade assays relative to its Neu2en analogue. These outcomes open the door for a new generation of potent inhibitors against hPIV-3 HN.

Probing Sialidases or Siglecs with Sialic Acid Analogues, Clusters and Precursors

“…At the same time, the equatorial C3 fluoride could interact with terminal nitrogen atom of other amino acids. Based on their inhibition assays and previous research, in general, a‐sialosyl fluorides bearing an equatorial, rather than an axial C3 fluoro‐substituent are more potent neuraminidase inhibitors, irrespective of the enzyme's origin …”

“…al. reported that 2,3‐difluorosialic acid derivative 30 exhibited enhanced potency in virus blockade assays and showed prolonged enzyme inhibition . They found the existence of a covalent intermediate formed by haemagglutinin‐neuraminidase protein and 30 through the phenolic oxygen atom of amino acid Tyr530 and the C2 atom of 30 .…”

The acidic hydrolysis ofN-acetylneuraminic 4,5-oxazoline allows a direct functionalization of the C5 position of Neu5Ac2en (DANA)

“…Several 2,3-unsaturated derivatives of the N-acetylneuraminic acid (Neu5Ac, 1) have been developed as potent inhibitors of sialidases, the glycolytic enzymes critical for bacteria and virus spread. [1][2][3][4][5][6] This class of inhibitors includes the 5-acetamido-2,6anhydro-3,5-dideoxy-D-glycero-D-galacto-non-2-enoic acid 2a (Neu5Ac2en, DANA), the N-triuoroacetylated congener 2b (FANA), the N-isobutyrylated one 2c (BCX 2798), and the 4-guanidino derivative 2d (Zanamivir), which has been widely used in the clinic against the inuenza virus ( Fig. 1).…”

Application of nucleophilic fluorinating reagents for the synthesis and transformations of cyclic β-amino acid derivatives

“…[22] Fluorinated sialic acid analogues, like 10, are sialidase (neuraminidase) inhibitors possessing potential antiviral activity. [53][54][55] In the case of α-amino acid mGluR4 agonist (±)-11, fluorination increased binding affinity nearly sevenfold. [56] Scheme 4.…”

“…Finally, both the O-acetyl groups and the methyl ester were hydrolyzed to obtain analogues 135-137 (Scheme 23). [55] Scheme 23. Synthesis of 2,3-difluorosialic acid analogues [55] 3.…”