Computational Tools for MNC
Computational Tools for Macromolecular Neutron Crystallography (MNC) is a consortium between Los Alamos National Laboratory (LANL) and Lawrence Berkeley National Laboratory (LBL). One of our first goals is to address the urgent need for new computational tools and methods to deal with the increasing number of neutron macromolecular structures to be determined and their increasing size and complexity. To that end, a patch, designated nCNS, for the existing structure solution program called CNSsolve has been developed which combines, for the first time, global X-ray, neutron and energy refinement with cross-validated maximum likelihood simulated annealing refinement. nCNS can therefore be used in an interoperable way for X-ray, neutron or joint X-ray and neutron analyses. The ultimate aim is to adapt these computational tools for incorporation into PHENIX. Neutron capabilities have been added to PHENIX, a collaborative project between several groups. Software phenix.refine offers a broad variety of efficient and fully automated tools for structure refinement using X-ray and neutron crystallography or both, such as restrained refinement at low resolution, simulated annealing and TLS modelling using maximum-likelihood targets, automatic detection and use of NCS, automatic detection and use of twinning information, sophisticated bulk-solvent correction and anisotropic scaling protocols, efficient handling of H atoms and proper refinement at ultra-high resolution. Our vision is to contribute to a computational workbench that structural biologists, with a range of experience, can use alternatively or at the same time for neutron or X-ray protein crystallography. The development of the neutron computational tools for nCNS and phenix.refine is funded by NIH-NIGMS grant (1R01GM071939) to Paul Langan and Paul Adams.  |
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