Derivation of the small-angle x-ray scattering functions for local conformations of polypeptide chains in solution.
The small-angle x-ray scattering (SAXS) functions are analytically derived for both the randomly coiled and helical local conformations of a polypeptide chain in solution. The resulting scattering functions for helices of various types are characterized by a maximum in the range of scattering-vector corresponding to Bragg spacings of 3-5 A, whereas the random-coil function has no maximum. This result is compatible with the extant SAXS data for partially neutralized poly(L-glutamic acid) and poly(L-lysine) in aqueous solutions. Comparison of the SAXS data with the calculated scattering functions shows that helical structures in both polypeptide chains are of the 3.6(13)-helix (alpha-helix) rather than 3.0(10)-type.
Muroga
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Department of Applied Chemistry, School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan.
D008958:Models, Molecular; D008962:Models, Theoretical; D010455:Peptides / Q000737:chemistry*; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D012996:Solutions; D014961:X-Ray Diffraction / Q000379:methods
D010455:Peptides; D012996:Solutions