title: Average protein density is a molecular-weight-dependent function.
abstract: The mass density of proteins is a relevant basic biophysical quantity. It is also a useful input parameter, for example, for three-dimensional structure determination by protein crystallography and studies of protein oligomers in solution by analytic ultracentrifugation. We have performed a critical analysis of published, theoretical, and experimental investigations about this issue and concluded that the average density of proteins is not a constant as often assumed. For proteins with a molecular weight below 20 kDa, the average density exhibits a positive deviation that increases for decreasing molecular weight. A simple molecular-weight-depending function is proposed that provides a more accurate estimate of the average protein density.
authors.affiliation: Institute of Physics, University of São Paulo, Rua do Matao Travessa R, 187 CEP 05508-900, São Paulo-SP, Brazil.
authors.forename: Hannes
authors.initials: H
authors.lastname: Fischer
authors.forename: Igor
authors.initials: I
authors.lastname: Polikarpov
authors.forename: Aldo F
authors.initials: AF
authors.lastname: Craievich
mesh_terms: D019295:Computational Biology / Q000379:methods; D003461:Crystallography; D008970:Molecular Weight; D011487:Protein Conformation; D011506:Proteins / Q000737:chemistry*; D014461:Ultracentrifugation
chemical_list: D011506:Proteins