[ccp4bb]: Disulfides between NCS related molecules

["Vajdos, Felix" <felix_vajdos@groton.pfizer.com>]

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Can someone explain to me how to establish a disulfide link for refmac5
between two NCS related monomers?  The problem is that the disulfide occurs
between molecule A and a molecule B in a different asymmetric unit.  I
thought I understood how to do this from Eleanor's response to a similar
question last year regarding links, but I cannot seem to make it work.

I have tried inserting the following SSBOND statement in my pdb file:

SSBOND   3 CYS A  427    CYS B  427                          1555   3646

The symmetry and origin shift I got from the output of act, (symmop 3,
origin shift of 1,-1,1).

I have also tried including in my input script:
MAKE SS Y
MAKE SYMM Y

Neither of these seems to work.  Refmac picks up two intramolecular
disulfides fine, but seems to ignore this intermolecular disulfide.


Thanks in advance!


Felix F. Vajdos
Pfizer Inc
Eastern Point Road
MS 4039
Groton, CT  06340

860-715-6504

The full input script is as follows:

refmac5 \
HKLIN   $inmtz \
HKLOUT   $REFMAC_SCR/${name}${curr}.mtz \
XYZIN   ./${name}${last}.pdb \
XYZOUT  ./${name}${curr}.pdb \
LIBIN   ${cplib} \
<< eor
LABIN FP=F SIGFP=SIGF  FREE=FreeR_flag
LABO FC=FC PHIC=PHIC    FWT=2FOFCWT PHWT=PH2FOFCWT -
                     DELFWT=FOFCWT  PHDELWT=PHFOFCWT
! We don't want any harvesting for cif files !
NOHARVEST
MAKE CHECK NONE
MAKE HYDR All
MAKE SS Y
MAKE SYMM Y
!
REFI TYPE RESTrained RESOLUTION  ${reslim}
REFI RESI MLKF
REFI BREF ISOTropic    
!
!
WEIGHT MATRIX ${matwt}
DAMP 0.5 0.5
!Scaling parameters:, use BAbinet's bulk solvent type scaling
SCAL TYPE BULK 
! and do anisotropic scaling
SCALE LSSC ANIS  
! estimate sigmaAs
SCALE MLSC
NCYC 20
MONI MEDI
BINS 20
end
eor




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