Observing the 1H NMR signal of the myoglobin Val-E11 in myocardium: an index of cellular oxygenation.

The 1H NMR signal from oxymyoglobin, a low-concentration diamagnetic protein, is visible in myocardial tissue. The methyl group of the Val-E11 resonates in a clear spectral region at -2.76 ppm and responds to dynamic changes in cellular oxygenation. With CO, the signal shifts to -2.4 ppm. The Val-E11 peak assignment and its response to oxygen and CO agree perfectly with previous myoglobin solution studies. Intracellular oxygen level can now be determined in vivo with the signal intensity ratio of oxymyoglobin/deoxymyoglobin, reflected by the Val-E11 and His-F8 peaks in the 1H NMR spectra. Moreover, protein structure-function relationship in vivo can now be probed.