Sticky triangles for experimental phasing

Traditionally crystallographic protein modelling and particularly model completion involves graphical display software for manual user interference.During the last decade, a number of software packages -such as ARP/wARP [1]emerged that do a large part of the crystallographic map interpretation and model building automatically without much manual work.This has tremendously shortened the time in which a macromolecular model could be built, from months and sometimes years to days or even a few hours.Having done a computer intensive map interpretation step there is generally no elaborate graphical communication or reporting framework, which would indicate how a model has progressed from a visually hardly interpretable density to an almost complete set of polypeptide fragments.As a result, the modelling needs to be viewed, judged and completed where needed elsewhere.At the same time, the recent past has shown that programs that allow semi-automatic modelling coupled with instantaneous graphical display -such as Coot [2] -are becoming very popular.To bridge the gap between the automation that the ARP/ wARP package offers and intuitive communication via graphical components, we have developed a graphical front end to ARP/wARP.It allows to run less time consuming tasks from the ARP/wARP suite, e.g.fitting ligands [3] or secondary structure [4].The user can choose the input from the graphical items and get results displayed immediately.The approach behind such a graphical tool is to not only provide in total more information than logfiles do on their own, but also at the same time to instantaneously allow the user to choose from minimal intervention to very informed guidance of the software.