# Studying large biomolecules as sedimented solutes with solid-state NMR

## TL;DR

A new method called sedimentation solid-state NMR is introduced to prepare large biomolecules for solid-state NMR studies without chemical treatment.

## Contribution

The novel sedimentation method avoids chemical treatments and enables solid-state NMR analysis of a wide range of soluble macromolecules.

## Key findings

- Sedimentation solid-state NMR can prepare non-crystalline protein solids suitable for ssNMR.
- The method preserves biological activity by avoiding chemical treatments.
- Loading tools were developed to streamline the sample preparation process.

## Abstract

Sedimentation solid-state NMR is a novel method for sample preparation in solid-state NMR (ssNMR) studies. It involves the sedimentation of soluble macromolecules such as large protein complexes. By utilizing ultra-high centrifugal forces, the molecules in solution are driven into a high-concentrated hydrogel, resulting in a sample suitable for solid-state NMR. This technique has the advantage of avoiding the need for chemical treatment, thus minimizing the loss of sample biological activity. Sediment ssNMR has been successfully applied to a variety of non-crystalline protein solids, significantly expanding the scope of solid-state NMR research. In theory, using this method, any biological macromolecule in solution can be transferred into a sedimented solute appropriate for solid-state NMR analysis. However, specialized equipment and careful handling are essential for effectively collecting and loading the sedimented solids to solid-state NMR rotors. To improve efficiency, we have designed a series of loading tools to achieve the loading process from the solution to the rotor in one step. In this paper, we illustrate the sample preparation process of sediment NMR using the H1.4-NCP167 complex, which consists of linker histone H1.4 and nucleosome core particle, as an example.