Dear CCP4 User,
                             I am new to crystallography and i need your valuable suggestion to help me out. We have crystallized full length protein and I am solving protein structure by molecular replacement method and molecular weight of protein is 37kDa.  Template pdb i am using have only C-terminal 24kDa protein structure. HKL2000 gave a space group C2221 and Mathews Coefficient indicate one molecule of 37 kDa with solvent content 17% only. When i am running phaser, it gave me a most probable molecualr weight of protein in ASU to be 23kDa. and also i am not getting any density for N-terminal of protein. Right now my Rwrk and Rfree are 28% and 37% but it not decreasing further.
When i am indexing in lower symetry sapce group P1211, most probable molecular weight ofpreotin com comes to be 46kDa in ASU. Would please anyone can help, and suggest me what is the real situation?.
Thanks in advance
Mathews table


Data line--- CELL 57.8080 70.0520 105.7080 90.0000 90.0000 90.0000
 Data line--- SYMM 'C 2 2 21'

Cell volume:        428071.531

For estimated molecular weight   36000.
Nmol/asym  Matthews Coeff  %solvent       P(2.30)     P(tot)
_____________________________________________________________
  1         1.49            17.30         1.00         1.00
_____________________________________________________________


Space-Group Name: C 2 2 21
   Space-Group Number: 20
   Unit Cell:   57.81   70.05  105.71   90.00   90.00   90.00
   MW of "average" protein to which Matthews applies: 36000
   Resolution for Matthews calculation:  2.30

   Z       MW         VM    % solvent  rel. freq.
   1       36000      1.49  17.25      0.002       <== most probable

   Z is the number of multiples of the total composition
   In most cases the most probable Z value should be 1
   If it is not 1, you may need to consider other compositions


   Histogram of relative frequencies of VM values
   ----------------------------------------------
   Frequency of most common VM value normalized to 1
   VM values plotted in increments of 1/VM (0.02)

        <--- relative frequency --->
        0.0  0.1  0.2  0.3  0.4  0.5  0.6  0.7  0.8  0.9  1.0 
        |    |    |    |    |    |    |    |    |    |    |   
   10.00 -
    8.33 -
    7.14 -
    6.25 -
    5.56 -
    5.00 -
    4.55 -
    4.17 --
    3.85 ---
    3.57 -----
    3.33 --------
    3.12 -------------
    2.94 -------------------
    2.78 ---------------------------
    2.63 ------------------------------------
    2.50 --------------------------------------------
    2.38 -------------------------------------------------
    2.27 --------------------------------------------------
    2.17 ---------------------------------------------
    2.08 -----------------------------------
    2.00 -----------------------
    1.92 -------------
    1.85 ------
    1.79 --
    1.72 -
    1.67 -
    1.61 -
    1.56 -
    1.52 -
    1.47 * (COMPOSITION*1)
    1.43 -
    1.39 -
    1.35 -
    1.32 -
    1.28 -
    1.25 -


   Most probable VM for resolution = 2.30957
   Most probable MW of protein in asu for resolution = 23168.4


Thanks in advance
Appu Kumar singh.