AUTOMATED REFINEMENT OF PROTEIN MODELS

An automated refinement procedure (ARP) for protein models is proposed , and its convergence properties discussed. It is comparable to the it erative least-squares minimisation/difference Fourier synthesis approa ch for small molecules. ARP has been successfully applied to three pro teins, and for two of them resulted in models very similar to those ob tained by conventional least-squares refinement and rebuilding with FR ODO. In real time ARP is about ten times faster than conventional refi nement. In its present form ARP requires high (2.0 angstrom or better) resolution data, which should be of high quality and a starting prote in model having about 75% of the atoms in roughly the correct position . For the third protein at 2.4 angstrom resolution, ARP was significan tly less powerful but nevertheless gave definite improvement, in the d ensity map at least.