J.L. is a medicinal chemist, whose research within the Zitzmann lab spans from organic synthesis to biophysical methods and virology. Novel molecules are synthesised, and then tested for binding to proteins using nuclear magnetic resonance (NMR) and other biophysical techniques. Promising compounds are tested in enzyme assays. The main targets are enzymes (the ER α-glucosidases and UGGT) of the Calnexin/Calreticulin cycle, a protein folding pathway in human cells that many enveloped viruses hijack to fold their own proteins. Compounds that effectively inhibit the enzymes are then tested for inhibition of viruses (including dengue, Zika, and SARS CoV-2).
J.L. originally joined the Zitzmann lab as a U.S. National Science Foundation Predoctoral Fellow while studying for a DPhil in Biochemistry and PhD in Organic Chemistry. As a Skaggs–Oxford Scholar, he completed the first portion of his thesis work at the Scripps Research Institute, working in the group of Prof. K. C. Nicolaou. There, he completed a synthesis of the carboline-disaccharide domain of the marine natural product, shishijimicin A. Before starting his doctoral work, he obtained his B.S. in chemistry from Rice University (Lovett College). During his undergraduate, J.L. worked with Prof. Jim Tour on the synthesis of molecular machines.
As well as research in the lab, J.L. is very interested in teaching and developing resources to support student learning. In the Department of Biochemistry, he provides lectures covering organic chemistry, carbohydrate chemistry and protein-ligand interactions. In addition, he is involved in practicals and workshops that complement the lecture courses, as well as classes for students pursuing the Aromatic and Heterocyclic supplementary subject. Since 2015, J.L. has been a Stipendiary Lecturer in Organic Chemistry and Biochemistry at Corpus Christi College, as well as providing tutorials at other colleges (including Lincoln and Trinity, among others).
An advocate of science outreach, J.L. contributes to the UNIQ Biochemistry courses offered to sixth form students annually. He has also been actively involved in the International Chemistry Olympiad since 2004, first as a member of the US delegation, then as a member of the International Steering Committee (2008 – 2012, 2016 – present). Since 2018, he has served as a member of the UK Chemistry Olympiad Working Group of the RSC, helping to design and run the national competition to select and train the UK team.
Targeting ER α-glucosidase I with a single-dose iminosugar treatment protects against lethal influenza and dengue virus infections; K. L. Warfield, D. S. Alonzi, J. C. Hill, A. T. Caputo, P. Roversi, J. L. Kiappes, N. Sheets, M. Duchars, R. A. Dwek, J. Biggins, D. Barnard, S. Shresta, A. M. Treston; N. Zitzmann; J. Med. Chem. 2020, 63, 8, 4205–4214 (2020).
ToP-DNJ, a selective inhibitor of endoplasmic reticulum α-glucosidase II exhibiting anti-flaviviral activity; J. L. Kiappes, M. L. Hill, D. S. Alonzi, J. L. Miller, R. Iwaki, A. C. Sayce, A. Caputo, A. Kato, N. Zitzmann; ACS Chemical Biology 13(1):60–65 (2017).