This script implements a version of the "Extended Guinier" method. Briefly, the method addresses the problem that for IDPs the region for which Guinier analysis is valid is usually a very small range of q in which the data is usually very noisy. An ansatz is developed for the next term of the expansion of I(q) such that a wider range of q can also be used to extract the radius of gyration (with the caveat that it is limited to disordered proteins in present form).
chmod a+x extended_guinier.py
./extended_guinier.py Nres datafile outfile
where:
Nres - number of residues in protein
datafile - experimental data
outfile - script output
datafile is expected to have the first two columns be q, I(q) and comment lines preceded by "#"
outfile has q**2, log[I(q)], log[I(q)]_fitted