title: Low-frequency motions in protein molecules. Beta-sheet and beta-barrel.
abstract: Low-frequency internal motions in protein molecules play a key role in biological functions. Based on previous work with alpha-helical structure, the quasi-continuum model is extended to the beta-structure, another fundamental element in protein molecules. In terms of the equations derived here, one can easily calculate the low-frequency wave number of a beta-sheet in an accordionlike motion, and the low-frequency wave number of a beta-barrel in a breathing motion. The calculated results for immunoglobulin G and concanavalin A agree well with the observations. These findings further verify that the observed low-frequency motion (or the so-called dominant low-frequency mode) in a protein molecule is essentially governed by the collective fluctuations of its weak bonds, especially hydrogen bonds, and the internal displacement of the massive atoms therein, as described by the quasi-continuum model.
mesh_terms: D007700:Kinetics; D008433:Mathematics; D008954:Models, Biological; D008958:Models, Molecular; D011487:Protein Conformation; D011506:Proteins / Q000378:metabolism*
chemical_list: D011506:Proteins