network models are widely used in the study of function-related slow motions of proteins. To reflect the correct fluctuations of proteins in solution, the heterogeneous interactions in proteins could be considered. In this work, the heterogeneous anisotropic network model (HANM) is applied to studythe protein dynamics in solutions. HANM could generate the accurate fluctuations of proteins and predict the important conformational changes related with their biological functions. By comparison of modes of HANM and principal components of NMR structures, it demonstrates that HANM can improve the description of slow motions of proteins in solution. (C) 2014 Elsevier B.V. All rights reserved.