In conventional MS,  the molecular weight is deduced from measurements of the m/z ratio. While exceedingly powerful, this approach is generally restricted to relatively homogeneous samples with MWs less than around a megadalton. MW distributions for heterogeneous samples such as highly glycosylated proteins cannot be measured by conventional MS, nor can MWs for very high molecular weight samples such as adenovirus (which has a MW of around 150 MDa). Charge detetion mass spectrometry (CDMS) has opened the door to accurate mass measurements for hetrogeneous ions with masses from kilodaltons to gigadaltons. In CDMS, the charge of each ion is measured along with its m/z. The charge can be measured acurately enough that charge states are well resolved in the charge spectrum. Results will be presented for several examples that showcase the value of CDMS for determining the stoichiometry of large assemblies. <br/>Adenovirus is one of the largest non-enveloped, double-stranded DNA virues. It is widely used as a gene therapy vector and has received a lot of attention recently as a novel vaccine platform for COVID-19. Human adenovirus 5 (HAdV5) contains over 2500 protein molecules and has a 36 kbp genome. Measurements for recombinant adenovirus vectors showing empty and full particles will be described along with studies of the disassembly of HAdV5 using CDMS, proteomics, and cryo-EM. <br/>Norovirus is a nonenveloped virus that causes acute gastroenteritis. It is the leading cause of foodborne illness in the United States, responsible for the loss of over $2 billion annually from lost productivity and related healthcare expenses. Norovirus has a T=3 capsid with 90 dimers of the major capsid protein VP1. CDMS has been used to investigate virus like particles (VLPs) assembled from VP1. The CDMS mass spectra show a series of sharp peaks that correspond to assemblies with specific numbers of VP1s. The numbers of VP1s in each assembly can be associated with their structures (i.e., 90 dimers indicates T=3, 120 dimers indicates T=4, etc). A rich variety of isosahedral and non-icosahedral structures were found. The structures present depend strongly on the solution conditions and the interconversion between different structures has been tracked.

Charge detection mass spectrometry and structural biology: Case studies

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.