Magic-angle N-15 NMR study of nitrate metabolism of Neurospora crassa

Magic-angle cross-polarization ¹⁵N nmr spectra of intact lyophilized mycelia from $\text{N.}\text{crassa}$ cultured on media containing ¹⁵N] nitrate have been obtained at 9.12 MHz. The time development of the uptake and distribution of label into protein and amino-acid metabolites can be observed directly. Nitrate metabolism is delayed about one hour if the cells innoculating the culture are grown on nitrate-free medium.