Bio

Christopher Callam received his undergraduate Chemistry degree (BS) from John Carroll University in 1998. He obtained his Ph.D. in Organic Chemistry from The Ohio State University working under the supervision of Dr. Todd Lowary in 2003. From 2003-2004, he was a Ruth L. Kirschstein NIH Post-Doctoral Research Fellow at the University of Pittsburgh working with Dr. Dennis Curran, In 2004, he returned to the Department of Chemistry at The Ohio State University.

Research Overview

The general area of our research is focused on synthetic organic chemistry. We are developing synthetic pathways for small molecule chemical reactivators for protection from organophosphorus agents, including chemical nerve agents and pesticides. Our research focuses on combating the effects of organophosphorus (OP) compounds. Organophosphorus (OP) compounds are inhibitors of acetylcholinesterase (AChE), an enzyme responsible for the rapid hydrolysis of acetylcholine (ACh). ACh is a neurotransmitter found in the central and peripheral nervous systems of humans and many other species; it plays key roles both in the transmission of action potentials and in muscle movement. AChE typically hydrolyzes acetylcholine to choline and acetate. OP compounds inhibit ACh activity by covalently binding to the active site residue. The phosphylated enzyme becomes increasingly resistant to reactivation, and a process called “aging” subsequently occurs. After aging occurs, current treatments are no longer effective options and new medical countermeasures must be developed to treat the aged form (resurrection).

We work with Dr. Christopher Hadad and Dr. Craig McElroy to develop novel drug-like molecules that are capable of reactivating and resurrecting OP-exposed AChE adducts. Collectively our investigator team conceives of novel structures for accomplishing the covalent chemistry involved in these processes.

Teaching

As the director of undergraduate organic laboratories, I have been heavily involved in various service activities for the Department, including management and mentoring of graduate and undergraduate teaching assistants, curriculum development, scheduling and enrollment for the organic course, and development of new lab experiments. I am interested in improving student understanding and incorporating technology into the organic chemistry lecture and laboratory.

Publications

Lovins, A. R.; Miller, K. A.; Homoelle, R. K.; Hoover, H. J.; McElroy, C. A.; Callam, C. S.; Hadad, C. M.; Imidazole as a Pendant Reactivation Ligand Increases Efficacy Scope for Reactivation and Resurrection of Organophosphorus-Inhibited/Aged Cholinesterases by Quinone Methide Precursors. ACS Chem. Neurosci. 4 March 2026; 17 (5): 962–975. DOI: 10.1021/acschemneuro.5c00631

Miller, K. A.; He, Y.; Allen, S. K.; McElroy, C. A.; Callam, C. S.; Hadad, C. M.; Unprecedented Alkylation of the Catalytic Histidine in the Aging of Cholinesterases after Inhibition by Organophosphorus Pesticides. Chem. Res. Toxicol. 17 March 2025; 38 (3): 503–518. DOI: 10.1021/acs.chemrestox.5c00031

Lovins, A. R.*; Miller, K.A.; Buck, A.K.; Ensey, D.S.; Homoelle, R.K.; Murtha, M.C.; Ward, N.A.; Shanahan, L.A.; Gutti, G.; Shriwas, P.; McElroy, C.A.; Callam, C.S.; Hadad, C.M. “4-Amidophenol Quinone Methide Precursors: Effective and Broad-Scope Nonoxime Reactivators of Organophosphorus-Inhibited Cholinesterases and Resurrectors of Organophosphorus-Aged Acetylcholinesterase.” ACS Chem. Neuro. 2024, 15(9), 1813-1827. DOI: 10.1021/ascchemneuro.4c00011

Clay, W.K.; Buck, A.K.; He, Y.; Hernandez Sanchez, D.N.; Ward, N.A.; Lear, J.M.; Nguyen, K.Q.; Clark, B.H.; Sapia, R.J.; Lalisse, R.F.; Sriraman, A.; Cadieux, C.L.; McElroy, C.A.; Callam, C.S.; Hadad, C.M. “Treatment of Organophosphorus Poisoning with 6-Alkoxypyridin-3-ol Quinone Methide Precursors: Resurrection of Methylphosphonate-Aged Acetylcholinesterase.” Chem. Res. Tox. 2024, 37(4), 643-657. DOI: 10.1021/acs.chemrestox.4c00024

Amoah, E.; Kulyk, D. S.; Callam, C.S.; Hadad, C.M.; Badu-Tawiah, A.* Mass Spectrometry Approach for Differentiation of Positional Isomers of Saccharides: Toward Direct Analysis of Rare Sugars. Anal. Chem. 2023, 95 (13), 5645-5642. DOI: 10.1021/acs.analchem.2c05375