Processing With Denzo

Chris Hosfield chris at crystal
Thu Jan 9 14:13:47 EST 1997

I was wondering if someone could be of assistance for the following
problem.  I have collected data on a protein crystal both at our home
source and at CHESS,and have processed the data with Denzo.  Using our
home source, which is equipped with a MAR Research image plate, we obtain
a triclinic P1 space group with unit cell axes and angles consistent from
crystal to crystal.  However, recently we have collected data at CHESS
using their Fuji image plates (The CCD detectors were being repaired) and
now, upon processing, we get the same space group P1, and nearly exactly
the same unit cell axes, and about the same angle beta, however the alpha
angle is decreased by about 7 degrees and the gamma angle is increasedby
about 8 degrees.  Note that occasionally beta, a, b and c change slightly 
as well (say two angstroms or two degrees)
        Considering that we have obtained the same cell dimensions
consistently at our home source, this is quite surprising.  One difference
has been the cryocooling we had to use at CHESS.  Could this be a factor?? 

Any help anyone could be would be greatly appreciated.


Chris Hosfield 
chris at 
Queen's University 
Kingston, ON 

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