15N NMR Studies of Nitrogen Metabolism in Intact Mycelia of Neurospora crassa

Abstract

Suspensions of intact mycelia of Neurospora crassa grown in medium containing 15NH4Cl have been found to give well-resolved 15N nuclear magnetic resonance spectra for metabolites that play crucial roles in intermediary nitrogen metabolism. These include the amide nitrogen of glutamine, the alpha-amino nitrogens of glutamate and other amino acids, the guanidino nitrogens of arginine, the ureido nitrogen of citrulline, the side-chain nitrogens of ornithine or lysine, or both, and uridine diphosphates. The turnover time of glutamine in vivo was estimated to be less than 1 hr by using nuclear magnetic resonance spectroscopy in conjunction with tracer methodologies. Applications of these techniques to the study of nitrogen metabolism are discussed.

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