The 1.8 A resolution structure of Alpha-chymotrypsin (CHT) dimer, which is asymmetrical, will be refined by restrained least squares methods. The details of the asymmetry of the refined structure of the independent molecules will be described and compared with other serine protease structures, most notably that of Gamma-CHT. The structure of a substrate transition state analogue complex will be determined at 1.8 A resolution to fix the exact nature of the boronate-Ser 195 tetrahedral intermediate and to observe the asymmetry of enzymic structural changes accompanying the interaction. Among other things, the results of these studies will serve as the basis of theoretical asymmetrical molecular dynamics calculations. The structure of a ternary complex of CHT, divalent Bowman-Birk inhibitor, trypsin will be determined to obtain models of enzyme-substrate interactions for CHT and trypsin, simultaneously. High resolution, low temperature studies at -100 Degrees C will be conducted on a new crystal form of CHT to determine the structure of an actual "immobilized" enzyme-substrate complex to fix the subsite interactions of the substrate peptide on either side of the scissile bond. Nucleic acidprotein subsite interactions will be also be studied with a high resolution structure determination of ribonuclease T(1) and appropriate nucleoside derivatives.