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grouped B-factors too low??

Pirkko Heikinheimo BTK pheikinh at arg.btk.utu.fi
Tue Oct 29 03:48:03 EST 1996

Dear X-PLOR users,

we are refining several structures from data collected in cryo temperatures
and have trouble refining the bfactors. We are starting off with the grouped
B-factor refinement at 2.3-2.5 A resolution. Currently my structure is at
2.3 A, with 27671 reflections used for 4620 atoms (560 residues and 179
waters). The problem is that if I refine the B-factors I end up with lots
of B-factors of 2.0 (the minimum) and at some places, lower B-factors for
the main chain than for the side chain portion. 

Is there some tricks that I should try, something related to cryo data
compared to the one collected at room temperature? Or is this just a
reflection of underfitting the data still, too many well ordered waters
that I just haven't modelled in yet? Solvent flattening?

Thank you for your help.

Pirkko Heikinheimo

Pirkko Heikinheimo
Turku Centre for Biotechnology,
P.O.Box 123,
FIN-20521 Turku, Finland

e-mail: pirkko.heikinheimo at btk.utu.fi
fax:    358-(0)2-333 8000
phone:  358-(0)2-333 8024


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