Structure Refinement and Map Calculation for Single Particle Analysis Using Servalcat

Abstract

Atomic model refinement and map calculation methods for cryo-EM single particle analysis（SPA）are explained in relation to X-ray crystallography. To make the best use of high-resolution reconstructions from SPA, it is important to calculate interpretable density maps to help build atomic models, and to use all experimental information to refine models. We developed a new program Servalcat to facilitate the structure refinement in reciprocal space. Servalcat performs structure refinement using REFMAC5, followed by calculation of weighted and sharpened F_o and F_o－F_c maps, which are useful in manual model rebuilding.