• Pair Distribution Distance Function (PDDF) or p(r): You can obtain the p(r) curve from SAXS experiments by indirect Fourier Transform (e.g. by GNOM software) of the experimental Intensity profile I(q) for the target protein in solution.

    SAXSTER uses the p(r) distribution in two-column format:

    As an example, the following are the r and p(r) for Lyzozyme protein:

    0.0 0.00000
    1.0 0.00179
    2.0 0.00382
    3.0 0.00608
    4.0 0.00857
    5.0 0.01130
    6.0 0.01423
    7.0 0.01736
    8.0 0.02066
    9.0 0.02405
    10.0 0.02751
    11.0 0.03094
    12.0 0.03426
    13.0 0.03738
    14.0 0.04020
    15.0 0.04264
    16.0 0.04460
    17.0 0.04602
    18.0 0.04682
    19.0 0.04698
    20.0 0.04648
    21.0 0.04536
    22.0 0.04364
    23.0 0.04139
    24.0 0.03871
    25.0 0.03570
    26.0 0.03245
    27.0 0.02914
    28.0 0.02582
    29.0 0.02260
    30.0 0.01960
    31.0 0.01685
    32.0 0.01440
    33.0 0.01228
    34.0 0.01047
    35.0 0.00897
    36.0 0.00772
    37.0 0.00671
    38.0 0.00588
    39.0 0.00519
    40.0 0.00461
    41.0 0.00410
    42.0 0.00363
    43.0 0.00319
    44.0 0.00276
    45.0 0.00233
    46.0 0.00190
    47.0 0.00145
    48.0 0.00099
    49.0 0.00051
    50.0 0.00000

    Reference:
    Svergun, D.I. Determination of the Regularization Parameter in Indirect-Transform Methods Using Perceptual Criteria. J. Appl. Crystallography 25, 495-503 (1992).