[sharp-discuss] statistics

[Clemens Vonrhein]

Dear sameeta,

Why do you think anything is wrong? The f'/f'' value for Th at CuKa
are -5.1024/12.3174 (see e.g CCP4 CROSSEC program). So that's 'not
bad'! If you have one Th for a smallish protein it can give very good
phasing power. Is the phasing power you quote the total over all
resolution or just one value at low resolution? Is it the ISO or ANO
value? For centrics or acentrics?

Have you tried to calculate phases in the 2nd hand? autoSHARP does
this automatically and will show two CC - one for each hand. What are
these two values? A good indicator of reasonable phases is if these
two values are quite different (say 0.1 versus 0.2). autoSHARP will
use the one with better CC as the 'correct hand' and do density
modification with this.

There could be a whole lot of reasons why you get a large phasing
power but

If you could send me the following files of the SHARP run:

  check_input.asc
  SIN

I could have a look at it.

Cheers

Clemens



>          well, i do not expect the Th derivative to be
> that good.... the data was collected on a rotatiing
> anode... the r-sym is 7.9 ...i/sigi is 17.5 ans i/sigi
> in highest resolution shell is 2.37.... completeness
> in the highest resolution shell is 78% and the data is
> upto 2.5A ...the overall completeness is 97.5%...i
> have got just one site and there doesnt seem to be any
> more peaks ...even pick peak doesnt show any peak
> grater than 4 sigma ...and yes the refinement did
> converge...the fom of the phases was 0.33 and the
> density modification step gave the correlation
> coefficient of 57%.... what could be wrong?????
>              thanking you 
>                      sameeta
> 
> =====
> Sameeta Bilgrami
> Research Scolar
> Deptt. of biophysics
> All India Instt. of Medical Scs.
> India
> 
> ________________________________________________________________________
> Looking for a job?  Visit Yahoo! India Careers
>       Visit http://in.careers.yahoo.com

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