DESCRIPTION (Adapted from abstract): Electron microscopy (EM) can provide structure determination of proteins, but only within labs having special facilities for cryomicroscopy. The traditional method to prepare protein specimens for EM, negative staining, only achieves resolution levels to 25 A. If defects in this methodology could be removed, data for secondary and tertiary structure of proteins than could be acquired by ordinary EM instruments. The chief objective is to develop new negative stains having the missing properties needed for higher resolution imaging with standard electron microscopes. Unexpected results have shown that heavy metals in traditional stains are not required to produce adequate contrast. The specific aims are to 1) systematically evaluate selected candidate light atom compounds for their ability to function as negative stains; 2) develop and optimize the conditions needed for their use in higher resolution imaging of proteins and 3) investigate and develop a negative stain cocktail by mixing several reagents, each contributing discrete functional capability needed for higher resolution imaging. Each negative stain will be evaluated by computer analysis of low-dose EM images of a standard crystalline test specimens.