Chapter 15, Problem 15.76EP

(a)

Interpretation Introduction

Interpretation: To classify ornithine in terms of nitrogen content as ${\text{N}}_1,{\text{ N}}_2,{\text{ N}}_3,{\text{ or N}}_4$.

Concept introduction: Ornithine is a nonstandard amino acid and accepts the entering carbamoyl phosphate group at the start of each cycle. It is encountered at step 1 of the urea cycle.

Depending upon the number of nitrogen atom present in the structure of the compound it can be classified as ${\text{N}}_1,{\text{ N}}_2,{\text{ N}}_3,{\text{ or N}}_4$ species. If a compound contains 1 nitrogen atom it is classified as ${\text{N}}_{\text{1}}$ species, if it contains 2 nitrogen atom it is classified as ${\text{N}}_{\text{2}}$ species and so on.

(b)

Interpretation Introduction

Interpretation: To characterize ammonium ion in terms of nitrogen content as ${\text{N}}_1,{\text{ N}}_2,{\text{ N}}_3,{\text{ or N}}_4$.

Concept introduction: Urea cycle is a cyclic biochemical pathway that involves the production of urea using ammonium ions and aspartate molecules as nitrogen sources. It converts toxic ammonium ion to urea which is then excreted from the body in urine.

The ammonium ion is the primary fuel for the urea cycle. Depending upon the number of nitrogen atom present in the structure of the compound it can be classified as ${\text{N}}_1,{\text{ N}}_2,{\text{ N}}_3,{\text{ or N}}_4$ species. If a compound contains 1 nitrogen atom it is classified as ${\text{N}}_{\text{1}}$ species, if it contains 2 nitrogen atom it is classified as ${\text{N}}_{\text{2}}$ species and so on.

(c)

Interpretation Introduction

Interpretation: To characterize aspartate in terms of nitrogen content as ${\text{N}}_1,{\text{ N}}_2,{\text{ N}}_3,{\text{ or N}}_4$.

Concept introduction: Aspartate is fuel for the urea cycle. It is encountered in step 2 of the urea cycle and undergoes a condensation reaction with citrulline to produce argininosuccinate.

Depending upon the number of nitrogen atom present in the structure of the compound it can be classified as ${\text{N}}_1,{\text{ N}}_2,{\text{ N}}_3,{\text{ or N}}_4$ species. If a compound contains 1 nitrogen atom it is classified as ${\text{N}}_{\text{1}}$ species, if it contains 2 nitrogen atom it is classified as ${\text{N}}_{\text{2}}$ species and so on.

(d)

Interpretation Introduction

Interpretation: To characterize arginine in terms of nitrogen content as ${\text{N}}_1,{\text{ N}}_2,{\text{ N}}_3,{\text{ or N}}_4$.

Concept introduction: Arginine is an essential amino acid. It is encountered in step 4 of the urea cycle. It undergoes hydrolysis to produce ornithine and urea.

Depending upon the number of nitrogen atom present in the structure of the compound it can be classified as ${\text{N}}_1,{\text{ N}}_2,{\text{ N}}_3,{\text{ or N}}_4$ species. If a compound contains 1 nitrogen atom it is classified as ${\text{N}}_{\text{1}}$ species, if it contains 2 nitrogen atom it is classified as ${\text{N}}_{\text{2}}$ species and so on.