Structure-Functional Characterization of Cytochrome P450 Sterol 14α-Demethylase (CYP51B) from Aspergillus fumigatus and Molecular Basis for the Development of Antifungal Drugs. Aspergillus fumigatus is the opportunistic fungal pathogen that predominantly affects the immunocompromised population and causes 600,000 deaths/year. The cytochr