Seeing the Invisible: 50 Years of Macromolecular Visualization

Brass Models: Placing Atoms into the Electron Density

Before computer graphics became sufficiently efficient, in the late 1970s, brass models were the standard, albeit difficult, way of interpreting the electron density image to construct a detailed atomic model of the protein.

Brass model pieces and tools

Brass model pieces, tools, & supports
On the floor of the case are a few representative peptide and tetrahedral carbon model pieces, connectors, and a wrench for tightening the connector screws. The brass vertical support rods and clamps were blackened for camouflage, by soaking in sodium thiosulfate solution (photographic "fixer", readily available from Dave's darkroom).

The Computer Graphics Lab at UNC Chapel Hill (GRIP-75)

Pioneering three-dimensional display technology at UNC graphics lab, ~1977
Crystallographic model-building for macromolecules was then a "driving problem" in computer science for the Computer Graphics Lab at UNC Chapel Hill, headed by Fred Brooks. Their Grip75 was the first successful software/hardware system for fitting a full atomic model into an electron density map, where the computer could constrain accurate local geometry. The Richardsons were the testers during development and the first to use it in practice, for SOD, followed by other visiting crystallographers.
[Britton E, Lipscomb JS, Pique ME, Wright, WV, Brooks FP Jr. The GRIP-75 Man-machine Interface. ACM SIGGRAPH Video Review, (4), (Aug. 1981)]
[Tainer et al. 1982, J. Mol. Biol. 160: 181]

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