This award provides funds for the improvement of techniques used in the preparation of crystals of single proteins for subsequent analysis by X-ray diffraction. The award will permit systematic studies of the growth of crystals of several well defined and widely available proteins by one of the leaders in this field. The data from these studies are expected to serve as an excellent reference for other investigators who wish to standardize and perfect their own technique. In recent years, X-ray crystallography has assumed a central role in the structural and functional analysis of enzymes and other proteins. Much of the progress in this area has been due to progress in the collection and analysis of the diffraction data; although there has been some progress in understanding the process of protein crystal growth, difficulty in growing crystals of sufficient size and quality remains a significant stumbling block in the analysis of most proteins. The kinds of studies to be undertaken by the awardee should help to make this aspect of structural studies more routine and thus to facilitate the analysis of many new proteins.