Usage:
ribspline  method  [ spec atom-spec ] [ smoothing none | strand | coil | both ] [ stiffness  s ]

bspline: tan; cardinal (unsmoothed): light blue; gray balls: α-carbon positions

Ribspline sets the method of ribbon path calculation:

• bspline or default - path smoothed over five successive residues, may not coincide exactly with any mainchain atoms
• cardinal - path smoothed over four successive residues, follows guide atom positions exactly unless additional smoothing is applied; to minimize the appearance of kinks, a tubular ribbon (for example, command: ribrepr rounded; ribscale licorice) may be preferred

The spec option allows limiting the command to certain models; molecule models containing any atom in atom-spec will be affected. Only one method can be used per molecule model.

The remaining options affect only the cardinal spline:

• whether to perform additional smoothing, and if so, for which types of secondary structure (helix and strand assignments are taken from the input structure file or generated with ksdssp):
  • none (default)
  • strand - peptide/protein strand
  • coil - peptide/protein nonhelix, nonstrand; nucleic acid
  • both - strand and coil
• stiffness or degree of resistance against changes in path direction (range 0.0-1.0, default 0.8)

See also: ribbon, ribbackbone, ribrepr, ribscale, ribclass, nucleotides, Ribbon Style Editor