BME PhD Defense Announcement for Tanmaye Nallan Chakravarthula (N. Alves and S. Harbin, co-chairs) Everyone is invited to attend the public presentation beginning at 12:00pm EST. Title: Modulating plasmin activity with multivalent inhibitors for drug delivery applications Date: November 22nd, 2022 Time: 12.00 PM EST Location: Zoom Meeting https://purdue-edu.zoom.us/j/95332317333?pwd=dXRvMlAwMG5SLy85L2VlQVZ6Uis0Zz0... Meeting ID: 953 3231 7333 Passcode: 582479 Thesis Committee: Dr. Nathan J. Alves (Advisor, Co-Chair) Dr. Sherry L. Voytik-Harbin (Co-Chair) Dr. David H. Thompson (Member) Dr. Luis Solorio (Member) Abstract: Plasmin is a crucial enzyme for blood clot digestion and for maintaining hemostatic balance. There is emerging interest in applying multivalency to achieve strong and highly controlled enzyme inhibition. Benzamidine is a competitive inhibitor of plasmin's active site whereas tranexamic acid (TXA) is an FDA-approved inhibitor that blocks plasmin's kringle domains. Herein, benzamidine and TXA were utilized to synthesize three classes of multivalent inhibitors (i) Multivalent benzamidines (ii) Multivalent TXAs, and (iii) Hetero-multivalent molecules having both benzamidine and TXA to evaluate their plasmin inhibition. These inhibitors were synthesized using amine-reactive chemistry, purified using RP-HPLC and confirmed with Mass Spectrometry. Inhibition assays were performed to assess inhibition potency by determining Ki values (inhibition constants). Lower Ki values indicate stronger inhibition. With multivalent benzamidine derivatives, it was observed that changing valency and linker length substantially impacted inhibition and resulted in Ki values ranging from 2.1 to 1,395 µM. Multivalent benzamidine inhibitors with higher valencies and shorter linker lengths exhibited stronger inhibition. Multivalent TXAs of valencies 1 to 16 were also tested and they exhibited Ki values varying from 2.5 to 21,000 µM indicating up to 8,400-fold improvement in inhibition due to valency. It was found that monovalent TXA, primarily a kringle inhibitor, was converted into a stronger active site inhibitor by multivalency. With hetero-bivalent TXA-dPEG36-AMB, simultaneous binding of benzamidine to the active site and TXA to the kringle domains was achieved to attain improved inhibition. These results indicate that multivalency can modulate plasmin inhibition and can significantly improve the potency of inhibitors.