Molecular basis of N-glycan recognition by pradimicin a and its potential as a SARS-CoV-2 entry inhibitor.

Virus entry inhibitors are emerging as an attractive class of therapeutics for the suppression of viral transmission. Naturally occurring pradimicin A (PRM-A) has received particular attention as the first-in-class entry inhibitor that targets N-glycans present on viral surface. Despite the uniqueness of its glycan-targeted antiviral activity, there is still limited knowledge regarding how PRM-A binds to viral N-glycans. Therefore, in this study, we performed binding analysis of PRM-A with synthetic oligosaccharides that reflect the structural motifs characteristic of viral N-glycans. Binding assays and molecular modeling collectively suggest that PRM-A preferentially binds to branched oligomannose motifs of N-glycans via simultaneous recognition of two mannose residues at the non-reducing ends. We also demonstrated, for the first time, that PRM-A can effectively inhibit severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in vitro. Significantly, the anti-SARS-CoV-2 effect of PRM-A is attenuated in the presence of the synthetic branched oligomannose, suggesting that the inhibition of SARS-CoV-2 infection is due to the interaction of PRM-A with the branched oligomannose-containing N-glycans. These data provide essential information needed to understand the antiviral mechanism of PRM-A and suggest that PRM-A could serve as a candidate SARS-CoV-2 entry inhibitor targeting N-glycans.

Evolved gas analysis with skimmer interface and ion attachment mass spectrometry for burnout monitoring of organic additives in ceramic processing.

A monitoring of the individual pyrolysis of mixed polymer as a binder for ceramic processing was carried out as an application of evolved gas analysis-mass spectrometry (EGA-MS) with a skimmer interface and ion attachment mass spectrometry (IAMS). It could detect characteristic species evolved by the pyrolysis of the organic additives, according to the instrumental advantages as the transmission of the gaseous species with no transformation by the skimmer interface and complete soft ionization for gaseous species by IAMS technique. Further, the pyrolysis behavior of blended polymers as a binder could be monitored individually as EGA curves of characteristic species evolved by the pyrolyses.