Katherine Mackenzie took a summer class from Professor Shaka and, several months later, asked if she could work in his lab. She took over a project from a graduating undergraduate researcher, considering the prior work while pursuing a new avenue of inquiry. In her research, Katherine enjoyed being able to apply the techniques and theories she learned in her classes. By experiencing the real-life situations to which her education could be applied she found it exciting to realize that the answers to puzzling research problems could be found in abstract theories. Katherine will graduate from UCI in Spring 2009, and hopes to go on to graduate school to pursue a Ph.D. in Chemistry.

The 1H-NMR spectra of carbohydrates are difficult to analyze because they exhibit spectral crowding. The compound trichloroacetyl isocyanate (TAI) replaces the hydroxyl groups of carbohydrates with protein-like structures containing NH groups. The NH groups appear downfield in the 1H-NMR spectra, allowing them to be counted. The proximal ring protons of TAI-derivatized carbohydrates become dispersed and can be identified as primary or secondary. TAI doubly enriched with 13C and 15N can be reacted with carbohydrates, producing a derivatized product with NMR-active isotopes. Multidimensional NMR analyses can then be carried out on the derivatized carbohydrates. This project was the development of a new synthesis procedure for TAI that would allow for isotopic enrichment. A novel procedure previously developed had low yield and was difficult to perform; this new procedure is more efficient and has a higher yield. 1H-NMR spectra of carbohydrates derivatized with unenriched TAI obtained from this procedure show the product is comparable to commercially obtained TAI and support the conclusion that this synthesis is a reasonable alternative to the one previously developed.

Athan J. Shaka School of Physical Sciences

Glycans are on the cutting edge of research in chemical signaling in biological systems, playing roles in immune response, cancer, and cell-cell signaling. Normally these sugars do not crystallize and therefore cannot be characterized by X-ray diffraction. In addition, the NMR spectrum of the unmodified glycan is usually intractable. However, by introducing a chemical group enriched with 15N and/or 13C (an “isotag”), much better NMR spectra can be obtained. The streamlined synthesis of trichloroacetylisocyanate that Ms. Mackenzie implemented gives us access to new options for characterization of this important class of molecules. Her work has been instrumental in making high-sensitivity multidimensional NMR of glycans a reality rather than a dream.