In vivo phosphorus and nitrogen metabolism

The specific fate and effects of various chemicals - helpful or harmful - on plants is of great importance in understanding plant metabolism and pathology (Gerendas and Ratcliffe, 2(XX)). The internal effects of ammonia/um nutrient can be monitored in vivo in maize roots via NMR NH3 concentration can be monitored by N-NMR and pH, and the phosphorylated species concentration can be measured by P-NMR and synthesis of carboxylate followed by -NMR. The specific fate of the NH3 can also be followed by N-NMR with isotopicaUy enriched feed species. 

Rather than follow the details of pH and ammonium metabolism of this experiment through, for the purposes of this chapter the reader needs only to understand that one 

3 Identification and quantification of small quantities in a complex mixture by 2D H- P-HMQC-TOCSY NMR 

The above problems are solved by doing a specific 2D NMR experiment an indirect heteronuclear correlation pulse program (HMCJC), which generates a 2D spectrum with its v-axis as a proton NMR scale and a y-axis as a P NMR scale a peak appears at a ( H, P) coordinate that identifies the bonded pair of atoms. The optimization of this experiment depends on timings which are governed by the 

There are various two-dimensional techniques for separating out specific interactions, connections or components besides HMQC. HMQC and HMQC-TOCSY are not restricted to P- H interactions more commonly they are used in C- H cases, but in general, as is clearly illustrated in this example, 2D NMR spreads out resonances compared with ID NMR so that desired components can be observed and quantified separately. 

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