The atomistic structures were generated using the VSOMM2, wherein each SOM model system comprised 1600 fragments in total, with each macromolecule consisting of 5 connected fragments. The pH was maintained at 5, and calcium ions were introduced to achieve charge neutrality. The water content was varied for each SOM model system (please refer to Table S2 in the Supporting Information). To ensure consistency with previous studies, the water content is reported as the heavy atom fraction of water, x water , determined from the corresponding atomistic system. These structures were subsequently converted into coarsegrained models using our newly developed tool. As the SOM composition remains constant across different water contents for each SOM type (model system), the parameterization procedure only needs to be performed once (i.e., for a single water content). The resulting topology files can then be used for the cases with other levels of water content. Additionally, the new tool allows to produce the mapped coarsegrained structure without the need for the parameterization step. These mapped structures were generated using the center of geometry mapping and subsequently solvated with gmx solvate.