Year of Publication


Degree Name

Doctor of Philosophy (PhD)

Document Type

Doctoral Dissertation




Pharmaceutical Sciences

First Advisor

Dr. Chang-Guo Zhan


Protein engineering has been a useful tool in the fight against human diseases. Human insulin was the first recombinant DNA-derived therapeutic protein (Humulin®) approved by the US FDA in 1982. However, many of the early protein drugs were only recombinant versions of natural proteins with no modification of their primary amino acid sequence and most of them did not make optimal drug products mainly due to their short half-life or suboptimal affinity, leading to poor therapeutic efficacy. The difficulty in the large-scale production of some therapeutic proteins was another important issue. In the past three decades, different protein engineering platforms have been developed to overcome the obstacles seen in the first generations of these treatments. With the help of these new techniques, proteins have been purposefully modified to improve their clinical potential. The focus of my dissertation is the engineering of potential protein drugs to make them therapeutically useful and more valuable. Previously, our research group has developed cocaine hydrolases (CocHs) from human butyrylcholinesterase (BChE) for treatment of cocaine addiction and prevention of acute cocaine intoxication. In the first project, CocHs were further engineered to improve their performance, e.g., Fc-fused CocHs with an extended serum half-life. Then, I investigated the potential application of a long-lasting CocH for protection against the acute toxic and stimulant effects of cocaine. In the second project, I investigated the potential inhibition of CocH-mediated cocaine hydrolysis by heroin (3,6-diacetylmorphine) or its initial host metabolite, 6-monoacetylmorphine (6-MAM). The investigation of this possible inhibition was important to determine the in vivo efficacy of CocHs, as heroin is one of the most commonly co-abused drugs by cocaine-dependent individuals, as well as a possible metabolite of CocHs. In the third project, I expressed and characterized the recombinant human UDP-glucuronosyltransferase 1A10 (UGT1A10) enzyme, which can inactivate many therapeutically valuable substances. In the fourth and final project, prostate apoptosis response-4 (Par-4), a tumor suppressor protein, was engineered to have a prolonged duration of action so that it may be more therapeutically valuable for cancer treatment.

Digital Object Identifier (DOI)