We describe an exercise intended to introduce students to the proton NMR experiments used to define the molecular conformation of biological molecules in solution. Proton NMR spectra of the octapeptide [sar1] angiotensin II are assigned and nuclear Overhauser effects are then used to develop constraints that define the three-dimensional shape of the peptide. The exercise demonstrates the utility of COSY, TOCSY, and NOESY types of experiments, while underscoring the limitations of these experiments in the determination of structure. The spectroscopic data used for the exercise are made available in several formats so that an instructor can design variations of the exercise to emphasize particular aspects related to data handling or the generation or comparison of derived structures. At least one quarter of biochemistry and a year of organic chemistry are reasonable prerequisites for the exercise, presuming that these courses provide the needed level of familiarity with the basic concepts of proton NMR spectroscopy. Junior- or senior-level chemistry and biochemistry students are probably most benefited from this exercise.
Supplement
Background information, experimental considerations, procedures, tables of chemical shifts, and a RASMOL drawing are included.
Our Secondary School editors work hard to distill all the JCE materials to produce a fraction of particular interest to high school teachers. We call it CLIC.
In recent years we have worked hard to better match our advertisers with our readers. When shopping for chemistry education materials, visit our advertisers' WWW sites first.
Take JCE along on your outreach missions. Copies of the Journal, guest access to JCE Online, our publications catalog, and more are available for your participants.