Deborah Fass grew up in the United States and studied at Harvard and MIT. Since her graduate research on retrovirus envelope proteins, she has been fascinated by protein folding, modification, assembly, and trafficking in the cell secretory pathway. In 1998 Deborah moved to Israel and set up a laboratory at the Weizmann Institute of Science. There, she and her students initiated the structural and biochemical characterization of flavoenzymes that produce de novo disulfide bonds for oxidative protein folding in the endoplasmic reticulum. Together with Carolyn Sevier, now at Cornell, she discovered a regulatory mechanism to prevent over-oxidation of the endoplasmic reticulum, such that sufficient reducing power is preserved for isomerization of mispaired cysteines. Flavin-containing sulfhydryl oxidases are also encoded by nucleocytoplasmic large DNA viruses. The Fass group determined the structures of a diverse set of these viral enzymes, demonstrating their remarkable structural evolution. More recently, her group has focused on the structure, dynamics, and function of a late-secretory disulfide catalyst, localized to the Golgi apparatus or secreted from cells. This enzyme is dramatically up-regulated in adenocarcinomas and surrounding stromal cells. Currently, Deborah and her group are exploring the value of blocking the enzyme’s activity to modulate the tumor microenvironment.