Doron Greenbaum, Ph.D.

Assistant Professor, Department of Pharmacology

Office Address:
School of Medicine
University of Pennsylvania
805 BRB II/III
421 Curie Boulevard
Philadelphia, PA 19104-6160

Telephone: (215) 746-2992
Fax:  (215) 573-9004
greenbaum@pharm.med.upenn.edu

RESEARCH SUMMARY

My laboratory will focus on developing and exploiting new technologies at the interface between biology and chemistry to study protease function. We will use a variety of techniques including the synthesis of small molecule inhibitors, quantitative proteomics, recombinant protein expression, and molecular genetics in order to better understand proteolytic systems. Although these tools are useful to study any biological system, my laboratory will initially concentrate much of its efforts to understand cysteine and serine proteases in the parasite P.falciparum, the causative agent of malaria.

Malaria is a devastating global disease causing at least 500 million clinical cases and more than 1 million deaths each year. Currently quinolines and anti-folates are the most commonly used drugs for disease prevention and treatment. However, multi-drug resistant Plasmodium falciparum has become a major problem. Therefore, discovery and investigation of known and/or novel targets for anti-malarial compounds is essential to develop new ways to combat this disease. The completed genome of P. falciparum is a rich resource in the search for targets of novel antimalarial therapies and allows the possibility of more systematic approaches to therapeutic discovery and design. In particular, the P. falciparum genome codes for a predicted 92 putative proteases representing all five classes: cysteine, metallo, aspartyl, threonine and serine, suggesting a complex role for proteases in intra-erythrocytic development. Cysteine and serine proteases are already considered to be promising chemotherapeutic targets for treatment of human malaria, and therefore a comprehensive understanding of their biological roles is essential.

Genomic and proteomic technologies have begun to address the challenge of assigning functions to the numerous proteins encoded by the multitude of sequenced prokaryotic and eukaryotic genomes. In particular, I believe chemical strategies for proteome analysis will become increasingly more important to enable functional characterization and profiling of enzyme activity on a global scale. Therefore I have developed universal chemical-based proteomics tools to functionally analyze the role of proteases in a variety of biological systems. I have also adapted these chemical tools to allow screening of small molecule libraries for specific inhibitors and drug design. My lab will continue to develop new chemical proteomic tools and small molecule libraries to facilitate protease drug target discovery, characterization and therapeutic design with a particular interest in malaria.

The chemical probes I developed were most recently employed to characterize the cysteine proteases within the human malaria parasite. One protease, falcipain 1, was found to be the primary cysteine protease active during the invasive stage of the parasite. In situ screening of a small molecule inhibitor library identified falcipain 1 specific compounds. Specific inhibition of falcipain 1 prevented invasion of parasites into host red blood cells. These results demonstrated the utility of functional proteomics methods and established a role for falcipain 1 in host cell invasion. My laboratory will continue to work to understand falcipain 1 function using both genetic and proteomics techniques. More recently I have begun to use both cysteine and serine inhibitors to characterize the novel SERA family of proteases and their roles in the rupture and invasion of host red blood cells.

In summary, my laboratory will focus on the following general areas of research:

(1) Malaria Protease Function- Functional characterization of malarial proteases using chemical, biochemical and genetic tools
(2) Activity-Based Probes- Development of new small molecule and macromolecular probes for proteases for genome-wide protease discovery and characterization
(3) Protease Substrate Discovery- Development of novel and adaptation of established proteomics techniques to uncover proteases substrates and proteolytic pathways
(4) Protease Biochemistry- Recombinant expression and characterization of protease specificity and inhibitor assay development

RECENT PUBLICATIONS