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Version 4 of HEAVY
I am pleased to announce that version 4 of HEAVY is now available. The
HEAVY program contains the "HEAVY" and "HASSP" heavy atom search,
refinement, and MIR/MAD phasing programs in an integrated package that
is easy to use and that runs on a variety of unix and VMS machines. Some
of the major new features of HEAVY are CORRELATED PHASING, BAYESIAN
WEIGHTING,
and BAYESIAN DIFFERENCE REFINEMENT (see below for brief descriptions of
these features).
New features of HEAVY:
- Correlated phasing allows you to make use of data from a set of
non-isomorphous derivatives that share the same non-isomorphism. In
effect, correlated phasing uses the information in the differences among
derivatives that is ignored by Blow-Crick phasing. If there is
correlated
non-isomorphism, these differences actually contain much of the phasing
information and using them can make a dramatic improvement in phasing
power.
- Bayesian weighting macromolecular atomic refinement consists of WEIGHTS
of the form WGT=1/(sigma**2+E**2) where the E**2 values are estimated from
rms differences between observed and calculated amplitudes of structure
factors. A structure factor file that can be read directly by X-PLOR is
generated. This weighting scheme leads to lower errors in coordinates
than unit weighting.
- iBayesian difference refinement is a method for refining a macromolecular
structure (a "variant") that is very similar to a structure that has
already been solved (the "native"). By refining differences between
native
and variant observed structure factor amplitudes against differences
between native and variant calculated structure factor amplitudes, very
accurate differences between the two structures can be obtained.
Difference
refinement requires that the native and variant structures be similar.
In
Bayesian difference refinement, an optimal weighting scheme for
combining
difference refinement and conventional refinement is used. Bayesian
difference refinement allows all the data for the variant structure to
be
used and represents a substantial improvement over both conventional and
difference refinement.
HOW TO GET HEAVY version 4:
HEAVY is distributed free of charge for
institution to sign a license agreement. To obtain a license, please
contact Nancy Cameron at the Los Alamos Industrial Partnership Office in
the following way:
E-mail to: Ncameron@lanl.gov
- Specify NON-COMMERCIAL or COMMERCIAL license
- If you are a University of California institution, say so
- Your name and email address. If you have an anonymous ftp site,
please list it.
- Name and address of person who will sign for your institution (i.e.,
person in your business office. This person will know if they can sign
for the institution. Faculty at universites cannot.)
- Node name(s) of single site or cluster of computers where HEAVY will
be used.
For further information on HEAVY: contact Tom Terwilliger
at terwilliger@lanl.gov
Please send your comments and your suggestions to Yves
Epelboin, epelboin@lmcp.jussieu.fr
.
Last update November 27 1995 Y.E.
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de l'Education Nationale
