Siegfried Leung, Ph.D., specializes in computational drug design and has over a decade of experience in macrocycle design and modeling. He joined Circle after undertaking postdoctoral research in the laboratory of Circle founder Matt Jacobson at UC San Francisco. His work there focused on the development of physics-based predictive models for passive membrane permeability and the application of these methods in designing cell permeable cyclic peptides. He was a key member of the Pfizer / Jacobson laboratory collaboration investigating the engineering of permeability into macrocyclic peptides, developing computational protocols for target-based design of permeable macrocycles. Siegfried received a B.S. (cum laude) from University of San Francisco and his Ph.D. in chemistry from Yale University under the mentorship of Prof. William Jorgensen.