“…Sample preparation by sedimentation allowed for the investigation of proteins that are difficult (or even impossible) to crystallize. Theoretically, the molecular mass of the protein determines the success of sedimentation, and proteins, such as the RNA polymerase subunits Rpo4/7 * (the * indicates that the Rpo7 unit is uniformly 13 C/ 15 N labeled) with a molecular weight of 34 kDa (Torosyan et al, 2019), the pRN1 primase with 40 kDa (Boudet et al, 2019), the neonatal Fc receptor with 40 kDa (Stöppler et al, 2018) as well as the human superoxide dismutase with 32 kDa (Fragai et al, 2013), the bacterial helicase DnaB with 708 kDa (Gardiennet et al, 2012), the iron-storage protein ferritin with 480 kDa (Bertini et al, 2012), a variety of supramolecular assemblies (Lecoq et al, 2018;Gauto et al, 2019), and PEGylated proteins (Ravera et al, 2016), were shown to form sediments suitable for solid-state NMR. This is for some of these systems probably a consequence of oligomerization that has been induced by the high protein concentrations (Bertini et al, 2013;Fragai et al, 2013).…”