text: Different methods have different levels of coverage and rates of calculation.  Some methods only calculate or predict chemical shifts for backbone atoms (6 atom types).  Some calculate chemical shifts for backbone and certain side chain atoms (C and N only) and still others are able to calculate shifts for all atoms (40 atom types).  For chemical shift refinement there is a need for rapid calculation as thousands of structures are generated during a molecular dynamics or simulated annealing run and their chemical shifts must be calculated equally rapidly.
  All the computational speed tests for SPARTA, SPARTA+, SHIFTS, CamShift, SHIFTX and SHIFTX2 were performed on the same computer using the same set of proteins. The calculation speed reported for PROSHIFT is based on the response rate of its web server.