Steve Ealick's Research Group Projects

We use X-ray crystallography to study the three-dimensional structures of proteins. The structural information is used for drug design, protein engineering, to understand catalytic mechanisms, and to explore protein evolution. Our group is also involved in the development of tools and techniques associated with synchrotron radiation, especially multiple wavelength anomalous diffraction (MAD), single wavelength anomalous diffraction (SAD) and microdiffraction. Our main projects include studies of enzymes involved in purine nucleotide metabolism and pyrimidine nucleotide metabolism, studies of enzymes involved in co-factor biosynthesis, especially thiamin biosynthesis and quinolinic acid biosynthesis, and enzymes involved in polyamine biosynthesis and purine biosynthesis.

Because of the role of purine and pyrimidine nucleotide metabolism in diseases such as cancer and viral infection, many of the enzymes involved are targets for drug design. We have focused considerable effort on nucleoside phosphorylases, which are found in both purine and pyrimidine pathways. Purine nucleoside phosphorylase is required for T-cell development. In collaboration with Professor Eric Sorscher, University of Alabama Medical School and Dr. William Parker, Southern Research Institute, we also study bacterial purine nucleoside phosphorylase because of its application in prodrug activation via gene therapy. With Dr. Mahmoud el Kouni at the University of Alabama at Birmingham, we are studying Toxoplasma gondii adenosine kinase with the objective of identifying differences from mammalian metabolism that may be exploited for new chemotherapeutic approaches.

Together with our collaborators, Professor JoAnne Stubbe at MIT, Dr. Robert White at Virginia Tech, and Dr. T. Joseph Kappock at Washington University, St. Louis, we are investigating enzymes involved in purine biosynthesis. Systematic investigation of an entire biochemical pathway provides important clues about protein evolution.

We are also interested in cofactor biosynthesis. We are currently focusing our efforts in this area on thiamin and quinolinic acid biosynthesis. Many of the reactions catalyzed by the enzymes in thiamin biosynthesis involve unprecedented chemistry and elucidation of catalytic mechanism is a major goal. By studying these enzymes, we have also discovered interesting evolutionary links to other pathways. Nicotinamide adenine dinucleotide (NAD) and its phosphate (NADP) are essential redox cofactors in all living systems; however, the biosynthesis of the key catalytic part of this cofactor, the quinolinic acid derived pyridine ring, is still poorly understood. Our studies are designed to characterize the pathway and to identify small molecule inhibitors. Pyridoxal 5'-phosphate (PLP) is the biologically active form of vitamin B6 and is an important cofactor for several of the enzymes involved in the metabolism of amine-containing natural products such as amino acids and amino-sugars. Of particular evolutionary interest is the finding that there are two distinct PLP biosynthetic pathways that have not yet been found to coexist in the same organism. Our primary collaborator for these studies is Professor Tadhg Begley of Cornell.

Polyamines have been implicated in many biological processes. Because of their alternating positive and hydrophobic regions, polyamines are able to bind to protein and nucleic acids in unique ways. Production of polyamines is highly regulated and is correlated with the cell cycle. We study enzymes of polyamine biosynthesis in collaboration with Professor Anthony Pegg of the Pennsylvania State University College of Medicine, Dr. Wayne Guida of the University of South Florida (USF) and the Moffitt Cancer Center at USF, and Dr. John Secrist III and Dr. William Waud of the Southern Research Institute. We plan to use the structures of these enzymes to design novel anticancer and antiparasitic drugs.

Finally, we are interested in synchrotron radiation and its application in macromolecular crystallography. Our group is leading an effort to construct and operate a facility at the Advanced Photon Source for technically challenging crystallographic studies. The Northeastern Collaborative Access Team (NE-CAT), with Professor Ealick as director, is operating undulator beamlines at Sector 24 of the Advanced Photon Source (APS) at Argonne National Laboratory in Argonne, Illinois. Of particular interest to the crystallographic community is the microdiffractometer we have deployed for analyzing much smaller crystals than those usually usable. We are also consolidating our operations by relocating the bending magnet beamline we had been operating at Sector 8 to Sector 2