Brian P. Callahan

Research in the Callahan lab blends chemistry and biology. They pursue challenging scientific problems that are relevant to human health and disease yet understudied. Projects can be hypothesis-driven or more technology-focused. The lab’s current work concentrates on the unusual biogenesis of hedgehog proteins, a family of cholesterol-modified hormones that function physiologically during embryo development and patho-physiologically during a variety of cancers. In general, the lab’s research projects follow three phases: Understand the chemistry of a biomolecular transformation; Apply that understanding to devise novel means to control the transformation with small molecules and/or mutagenesis; Integrate this synthetically controlled transformation into living cells and eventually into multicellular organisms to address significant questions in biomedicine. Research techniques: Recombinant protein expression; analytical chromatography; enzyme kinetic assays; protein engineering; synthetic chemistry; small molecule screening; bioconjugation; mammalian cell culture; flow cytometry; fluorescence microscopy; photoaffinity labeling.

Xu Z, Zhang X, Pal C, Rozners E, Callahan BP. Enzyme Fragment Complementation Driven by Nucleic Acid Hybridization. Bioorganic Chemistry 2025 154, 108039. Callahan BP, Xu Z. There's more to enzyme antagonism than inhibition. Bioorg Med Chem. 2023 Mar 15;82:117231. doi: 10.1016/j.bmc.2023.117231 (Review) Ciulla DA, Xu Z, Pezzullo JL, Dranchak P, Wang C, Giner JL, Inglese J, Callahan BP. Paracatalytic induction: Subverting specificity in hedgehog protein autoprocessing with small molecules. Methods Enzymol. 2023;685:1-41. (Book Chapter) A cell-based bioluminescence reporter assay of human Sonic Hedgehog protein autoprocessing to identify inhibitors and activators. Ciulla DA, Dranchak P, Pezzullo JL, Mancusi RA, Psaras AM, Rai G, Giner JL, Inglese J, Callahan BP. J Biol Chem. 2022 Dec;298(12)