Hi Ian,

The warning refers to a MET 59 in chain A whereas you only have MET 72. That
is very suspicious. Non-sequential residues further apart than x Angstrom
automatically get a gap record. Have you tried a newer version of Refmac,
because this feature was added quite a while ago?
What is your setting for 'MAKE CONN' when you run Refmac?

Cheers,
Robbie



> -----Original Message-----
> From: CCP4 bulletin board [mailto:[email protected]] On Behalf Of
> Ian Tickle
> Sent: Monday, February 18, 2013 17:32
> To: [email protected]
> Subject: [ccp4bb] Link problem with Refmac.
> 
> 
> All, I'm having a problem with Refmac (v. 5.7.0025) that I don't
understand.
> It's linking 2 residues that it shouldn't be.  Here's the relevant message
in the
> log file:
> 
>   WARNING : large distance for conn:TRANS    dist =    10.768
>             ch:AA   res:  58  THR             -->  59  MET
ideal_dist=     1.329
> 
> Note that there are no LINK (or LINKR) records in the PDB header.
> 
> 
> Here are the input co-ords for the relevant residues (not linked):
> 
> ATOM    887  N   THR A  58      13.587   1.365  19.814  1.00 14.28      A
N
> ATOM    888  CA  THR A  58      14.743   1.126  18.960  1.00 17.64      A
C
> ATOM    890  CB  THR A  58      14.325   0.613  17.567  1.00 17.69      A
C
> ATOM    892  OG1 THR A  58      13.605   1.650  16.879  1.00 15.24      A
O
> ATOM    894  CG2 THR A  58      13.505  -0.658  17.658  1.00 17.33      A
C
> ATOM    898  C   THR A  58      15.573   2.346  18.631  1.00 22.80      A
C
> ATOM    899  O   THR A  58      15.144   3.492  18.842  1.00 20.41      A
O
> ATOM    956  N   MET A  72      13.605  -6.845  13.378  1.00 43.23      A
N
> ATOM    957  CA  MET A  72      12.268  -6.980  12.733  1.00 39.06      A
C
> ATOM    959  CB  MET A  72      12.308  -6.361  11.331  1.00 42.06      A
C
> ATOM    962  CG  MET A  72      12.455  -4.846  11.320  1.00 43.45      A
C
> ATOM    965  SD  MET A  72      13.020  -4.153   9.755  1.00 46.07      A
S
> ATOM    966  CE  MET A  72      14.695  -4.789   9.653  1.00 49.84      A
C
> ATOM    970  C   MET A  72      11.544  -8.344  12.624  1.00 36.94      A
C
> ATOM    971  O   MET A  72      10.314  -8.353  12.558  1.00 34.24      A
O
> 
> 
> Here are the same residues (linked) after refinement:
> 
> ATOM    887  N   THR A  58      14.212   0.104  18.340  1.00 43.09      A
N
> ATOM    888  CA  THR A  58      14.332  -1.166  17.541  1.00 45.12      A
C
> ATOM    890  CB  THR A  58      12.906  -1.657  17.309  1.00 39.26      A
C
> ATOM    892  OG1 THR A  58      12.400  -1.039  16.117  1.00 38.40      A
O
> ATOM    894  CG2 THR A  58      12.010  -1.301  18.435  1.00 33.96      A
C
> ATOM    898  C   THR A  58      14.805  -1.376  16.064  1.00 59.98      A
C
> ATOM    899  O   THR A  58      15.304  -0.470  15.386  1.00 69.73      A
O
> ATOM    901  N   MET A  72      14.609  -2.641  15.623  1.00 61.67      A
N
> ATOM    902  CA  MET A  72      13.990  -2.997  14.308  1.00 60.32      A
C
> ATOM    904  CB  MET A  72      14.898  -2.730  13.093  1.00 71.29      A
C
> ATOM    907  CG  MET A  72      14.126  -2.345  11.812  1.00 73.22      A
C
> ATOM    910  SD  MET A  72      12.912  -3.499  11.087  1.00 69.42      A
S
> ATOM    911  CE  MET A  72      13.917  -4.503   9.996  1.00 63.68      A
C
> ATOM    915  C   MET A  72      13.413  -4.438  14.205  1.00 59.57      A
C
> ATOM    916  O   MET A  72      12.199  -4.599  14.130  1.00 60.33      A
O
> 
> 
> Residues 59-71 are present but in a poorly defined loop so I definitely do
not
> want residues 58 & 72 linked!  I'm puzzled because I'm sure it never used
to
> do this, i.e. you had to specify a LINK if you wanted one and Refmac was
> smart enough to recognise that residues across a break should not be
linked.
> So how do I tell it NOT to link them?
> 
> 
> Cheers
> 
> 
> -- Ian
> 

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