Energetics of the structure of the four-alpha-helix bundle in proteins.
AUTOR(ES)
Chou, K C
RESUMO
The main features of the four-alpha-helix bundle, one of the characteristic structural elements of many proteins, can be explained in terms of noncovalent interactions between the constituent helices. Conformational energy computations have been carried out on four types of four-alpha-helix bundles, each consisting of four CH3CO-(L-Ala)10-NHCH3 polypeptide chains, with various combinations of parallel and antiparallel orientations of the helices. In the bundle with the most favorable energy, all pairs of neighboring helices are oriented antiparallel--i.e., in the orientation that is favored by electrostatic interactions between the helices. In this structure, the orientation angle between neighboring helix axes is -168 degrees, within +/- 7 degrees, in close agreement with the orientation angles observed in proteins and with the value that we computed earlier for the most favorable packing of pairs of interacting alpha-helices. This orientation corresponds to a left-handed twisting of the helical bundle. The preferred handedness of this twisting arises as a result of favorable nonbonded interactions between the alpha-helices.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=280415Documentos Relacionados
- Topological distribution of four-alpha-helix bundles.
- Role of loop-helix interactions in stabilizing four-helix bundle proteins.
- Sequence determinants of the energetics of folding of a transmembrane four-helix-bundle protein
- Myocardial activation of the human cardiac alpha-actin promoter by helix-loop-helix proteins.
- alpha-Helix dipole model and electrostatic stabilization of 4-alpha-helical proteins.