This proposal is for the purchase of a computer graphics machine with which to present real time manipulative high resolution pictures of molecules. This service instrument will supply stick, space filling and accessible surface area representations of proteins and nucleic acids, together with energy minimization and display of large organic and metallo-organic molecules. Specific projects proposed for the use of the instrument are interpretation of chemical mapping experiments with thrombin; visualization of macromolecular structures such as lactose synthase and 5S and 5.8S RNA; protein disulfide accessibilities to CO2-; peptide modelling for semisynthetic RNase; stereochemical consequences of Mg ATP-Myokinase fragment interactions and of pyridoxal phosphate/substrate interactions in racemases and epimerases, visualization of membrane bilayers; and visualization of metallo-lacunar dioxygen carriers and large organic compounds; e.g. boromycin, thiostreptone, and cyclooctatetraenes.