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Doctoral Dissertation Announcement
Candidate: Brian A. Zeider
Doctor of Philosophy
Title: Biophysical Characterization of Theromin a Novel Leech Inhibitor and Interactions of the Fourth Domain of Wilson Disease Protein and Its Copper(I) Chaperone HAH1
Dr. David Huffman, Chair
Dr. Susan Stapleton
Dr. Ekkhard Sinn
Dr. Thomas Thamman
Date: Friday, October 29, 2010 9:30 a.m. to 1130 a.m.
2722 Wood Hall
The blood clotting process is tightly controlled in order to limit coagulation to the site of injury. Thrombin, a serine protease, catalyzes a final step of the blood coagulation cascade. Typically, inhibition of thrombin is accomplished by administration of the drug heparin, which stimulates the production of the endogenous inhibitor – antithrombin. A substance that directly targets thrombin is preferred as a more potent, rapidly acting anticoagulant. A new inhibitor peptide named theromin was recently identified in the leech Theromyzon tessulatum and is the most potent inhibitor isolated to date. The amino acid sequence of theromin is quite different from that of previously isolated thrombin inhibitors and instead it bears resemblance to a known class of metal-binding peptides, namely the metallothioneins. The researchers have synthesized the gene for theromin and integrated it into an expression vector to produce recombinant theromin, as well as described the inhibition kinetics and copper binding.
Copper is scrupulously regulated within the cell to maintain proper balance of redox activity and storage. One protein involved in this process is Wilson disease protein, which is responsible for moving copper into vesicles for either storage or removal from the cell. Previous work has shown copper is transferred to the Wilson disease protein via its metallochaperone, HAH1. The proposed mechanism for this transfer seems to involve a transient 3-coordinate copper(I) intermediate. Similar work done on Saccharomyces cerevisiae has shown that a 3-coordinate intermediate could exist between Atx1 (analogue of HAH1) and its partner Ccc2. Trapping this intermediate involved selective mutation of individual cysteines involved in the copper(I) binding.