Protein model determination from crystallographic data.

Crystallographic studies play a major role in current efforts towards protein structure determination. However, despite recent advances in computational tools for molecular modeling and graphics, the task of constructing a model of the tertiary structure of a protein from experimental data remains complex and time-consuming, requiring extensive expert intervention. This paper describes an approach to protein model determination that incorporates crystallographic data, along with sequence data. A model is represented as an annotated graph that traces the backbone and side chains for a protein. The proposed approach incorporates numerical techniques that are applied to construct and analyze an electron density map for a unit cell of a crystal. The purpose of this work is to advance the ability to discern meaningful features of protein structure through the use of topological analysis of the relative density. Experimental results, which demonstrate the viability of the approach, are reported.