solvent correction?

[ravi@cmb2.saha.ernet.in (S.Ravichandran)]

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Hello all,

	Well, the question is asked many times before.. But, I am raising
this again, now..

        Why is the low-resolution R-factor values are VERY high when the
bulk solvent correction is applied using REFMAC.??

	I think many people have pointed out the 'scaling' method involve 
there.. as the method is basically applied using Babinet principle?


I have the following result, when I use REFMAC (with SCALE TYPE BULK)..


12.500   9.774      75  11    98.228     7.352  0.591  0.768       5     0.501
 9.774   8.024     111   4    90.251     6.372  0.412  0.493      18     0.344
 8.024   6.805     173   2    82.447     4.868  0.340  0.392      14     0.234
 6.805   5.908     216  ?     80.333     6.413  0.275  0.330      27     0.302
etc.....
etc....

(watch-out the columns 7,8 and 10 for R, wR and Rfree)

	Surprisingly, when I use REFMAC combined with CNS..
(with FPART and PHIPART, taken after CNS bulk-solvent correction and using 
SCALE TYPE SIMPLE)....

these values are...


12.500   9.774      75  11    97.998     6.652  0.285  0.370       5     0.309
 9.774   8.024     111   4    91.021     6.178  0.232  0.296      18     0.242
 8.024   6.805     173   2    79.077     5.368  0.243  0.296      14     0.217
 6.805   5.908     216  ?     81.293     5.518  0.245  0.290      27     0.290
etc....
etc....

(now watch-out those columns.. 7,8 and 10 !!!)......

   	I guess the bulk-solvent plays a major role in controlling these
low-resolution part, as in CNS it is not the same 'Babinet principle'..
(It uses a solvent-masking procedure....??)..

Sincerely,
Ravi.

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| S.Ravichandran                              e-mail:-                |
| Crystallography &                           ravi@cmb2.saha.ernet.in |
| Molecular Biology Division,                 ravichu@hotmail.com     |
| Saha Institute of Nuclear Physics                                   |
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