The folding protein problem, how a protein's amino-acid sequence relates to its folded shape, is the most important unsolved problem facing computational biochemistry. Yong Duan, Lu Wang and Peter Kollman used PSC's Cray T3D and resources at Cray Research to perform a microsecond simulation of the folding of a small protein, the villin headpiece. This image shows a snapshot along the computed folding pathway. The computation by the Kollman group is two orders of magnitude longer than the longest precious calculation of its kind and has identified the initial collapse of the protein to a "molten globular state" from which it searches for the ultimate fold.