Virus-like particle size and molecular weight/mass determination applying gas-phase electrophoresis (native nES GEMMA)

Abstract

Bio-)nanoparticle analysis employing a nano-electrospray gas-phase electrophoretic mobility molecular analyzer (native nES GEMMA) also known as nES differential mobility analyzer (nES DMA) is based on surface-dry analyte separation at ambient pressure. Based on electrophoretic principles, single-charged nanoparticles are separated according to their electrophoretic mobility diameter (EMD) corresponding to the particle size for spherical analytes. Subsequently, it is possible to correlate the (bio-)nanoparticle EMDs to their molecular weight (M W) yielding a corresponding fitted curve for an investigated analyte class. Based on such a correlation, (bio-)nanoparticle M W determination via its EMD within one analyte class is possible. Turning our attention to icosahedral, non-enveloped virus-like particles (VLPs), proteinaceous shells, we set up an EMD/M W correlation. We employed native electrospray ionization mass spectrometry (native ESI MS) to obtain M W values of investigated analytes, where possible, after extensive purification. We experienced difficulties in native ESI MS with time-of-flight (ToF) detection to determine M W due to sample inherent characteristics, which was not the case for charge detection (CDMS). nES GEMMA exceeds CDMS in speed of analysis and is likewise less dependent on sample purity and homogeneity. Hence, gas-phase electrophoresis yields calculated M W values in good approximation even when charge resolution was not obtained in native ESI ToF MS. Therefore, both methods-native nES GEMMA-based M W determination via an analyte class inherent EMD/M W correlation and native ESI MS-in the end relate (bio-)nanoparticle M W values. However, they differ significantly in, e.g., ease of instrument operation, sample and analyte handling, or costs of instrumentation.

N-terminal VP1 Truncations Favor T = 1 Norovirus-Like Particles

“…nES GEMMA spectra of the second batch showed a predominant species at 24.50 ± 0.12 nm equaling T = 1, as well as a species with low counts at 30.71 ± 0.17 nm. The population at 30.71 nm was assigned to 6.24 MDa using VLP correlation fitting approximately 120 VP1 (Table S3) [28]. At pH 9, high-mass particles in batch 1 were fragile, complementing our previous findings with native MS [25], while the T = 1 VLPs in batch 2 were resistant to pH 9.…”

Exceeding a resolving power of 50 for virus size determination by differential mobility analysis

“… Fernandez de la Mora, 2015 ; Fernandez de la Mora, 2018 ; Lübbert and Peukert, 2019 ; Perez-Lorenzo et al, 2020 ; Procházkováa et al, 2018 ; Ribière et al, 2010 ; Trimpin et al, 2007 ; Uetrecht et al, 2010 ; Weiss et al, 2019 .…”

Mass Spectrometry-Based Structural Virology

“…In the case of m/z -based mass estimation, nucleic acid containing particles typically acquire less charges and populate higher m / z regions than purely proteinaceous assemblies, 30 and for GEMMA, particles with variable amounts of cargo, and thus mass, will provide indistinguishable EMDs. 40 , 41 …”