title: Normal mode analysis of G-actin.
abstract: We undertook a normal mode analysis of the G-actin monomer bound with ADP and Ca2+, in order to better understand the internal modes of this protein. The internal co-ordinates consisted of 1373 single bond torsions, plus an additional 11 torsions to parameterize the motion of the nucleotide and cation with respect to the protein. A generalized eigenvalue problem was solved to yield a complete description of the motion in the 0.1 to 17.0 picosecond time range. The modes were visualized using an interactive graphics routine. The softest, slowest modes include a propeller-like twisting of the large and small domain about the phosphate binding loops, a rolling of subdomain 4 about an alpha-helix axis and a scissor-type opening and closing of the ADP-binding cleft. The computed temperature factors agree well with experimental ones. A comparable analysis done on G-actin-ATP shows that the softest modes are almost identical.
authors.affiliation: Max-Planck-Institut für medizinische Forschung Abteilung Biophysik, Heidelberg, Germany.
authors.forename: M M
authors.initials: MM
authors.lastname: Tirion
authors.forename: D
authors.initials: D
authors.lastname: ben-Avraham
mesh_terms: D000199:Actins / Q000737:chemistry* / Q000648:ultrastructure; D000244:Adenosine Diphosphate / Q000737:chemistry; D000255:Adenosine Triphosphate / Q000737:chemistry; D002118:Calcium / Q000737:chemistry; D003461:Crystallography; D066298:In Vitro Techniques; D009038:Motion; D017434:Protein Structure, Tertiary; D013816:Thermodynamics
chemical_list: D000199:Actins; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D002118:Calcium