Hello Vandana, so you are saying your Rfree=27.7 and Rwork=27.0.

Let's stop shaking the air with throwing out hypothesis (someone, likely you, will need to verify them and this is some work) and start with the simplest option -- look in PDB at the structures deposited at similar resolution as yours, that is in the range, say, from 2.9 to 3.1A:

Histogram of Rwork for all model in PDB at resolution 2.9-3.1:
     0.139 - 0.160      : 1
     0.160 - 0.181      : 16
     0.181 - 0.202      : 122
     0.202 - 0.223      : 251
     0.223 - 0.243      : 259
     0.243 - 0.264      : 161
     0.264 - 0.285      : 69 <<< your structure
     0.285 - 0.306      : 21
     0.306 - 0.327      : 8
     0.327 - 0.348      : 4
Histogram of Rfree for all model in PDB at resolution 2.9-3.1:
     0.181 - 0.205      : 4
     0.205 - 0.229      : 35
     0.229 - 0.254      : 128
     0.254 - 0.278      : 274 <<< your structure
     0.278 - 0.302      : 285
     0.302 - 0.326      : 127
     0.326 - 0.350      : 46
     0.350 - 0.375      : 9
     0.375 - 0.399      : 2
     0.399 - 0.423      : 2
Histogram of Rfree-Rwork for all model in PDB at resolution 2.9-3.1:
    -0.025 - -0.008     : 3
    -0.008 - 0.010      : 20 <<< your structure
     0.010 - 0.027      : 100
     0.027 - 0.045      : 269
     0.045 - 0.062      : 315
     0.062 - 0.080      : 133
     0.080 - 0.097      : 54
     0.097 - 0.115      : 12
     0.115 - 0.132      : 3
     0.132 - 0.150      : 3

Hm... I think you got the message. Not necessarily your structure is incorrect, it just simply needs some closer look and possibly some more work -:) It might turn out that a few cycles of refinement just enough.

Please let me know if you want to discuss it some more.

All the best!
Pavel.

On 10/9/09 12:28 AM, Vandana Kukshal wrote:

[log in to unmask]" type="cite">hi
i am solving one structure

in which after refinement i got R factor=27
and R free =27.7
i want to know that is it correct or i did some over refinment

the Resolution is 3.0 A