There is an urgent need to augment the widely-used and well-tolerated but drug resistance-susceptible triazole drugs with broad-spectrum antifungals that target fungal lanosterol 14 alpha-demethylase (Erg11p) and not human CYP51. We have obtained high-resolution X-ray crystal structures of yeast Erg11p with substrates and triazole inhibitors bound. We will apply our unique knowledge of cytochrome P450 structure and function and use a comprehensive set of screens to identify new antifungals. Our research will confirm key biochemical properties of the enzyme, identify a product egress pathway, and resolve the structures of the Erg11ps of several important fungal pathogens and human CYP51. Computer aided drug design, yeast-based high throughput screens, secondary screens, counterscreens plus a combinatorial chemistry capacity will be used to identify efficiently optimal hits as Erg11p-specific drug candidates. The identification of new classes of antifungals will provide models for drug discovery and development that circumvent the ubiquitous activities of cytochrome P450 enzymes.