Chapter 15, Problem 15.75EP

(a)

Interpretation Introduction

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

Concept introduction: Carbamoyl phosphate is an intermediate or one of the fuel for the urea cycle. Ammonium ion produced via oxidative deamination reaction is converted into the carbamoyl phosphate which then enters the urea cycle.

The carbamoyl phosphate formation reaction is carried out in the mitochondrial matrix. Carbamoyl is the prefix used to represent an amide group. Thus carbamoyl phosphate is a molecule that contains a phosphate group attached to an amide functional group.

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.

Answer to Problem 15.75EP

Carbamoyl phosphate is a ${\text{N}}_{\text{1}}$ species.

Explanation of Solution

Carbamoyl phosphate and aspartate are fuel for the urea cycle. The structure of carbamoyl phosphate is:

It contains only one nitrogen atom thus carbamoyl phosphate is characterized as ${\text{N}}_{\text{1}}$ species.

(b)

Interpretation Introduction

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

Concept introduction: Glutamate is conjugate anion of glutamic acid. Glutamic acid is an amino acid. 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.

Answer to Problem 15.75EP

Glutamate is a ${\text{N}}_{\text{1}}$ species.

Explanation of Solution

The structure of glutamate is:

It contains only one nitrogen atom thus glutamate is characterized a ${\text{N}}_{\text{1}}$ species.

(c)

Interpretation Introduction

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

Concept introduction: The nitrogenous product of protein metabolism is converted to urea via urea cycle. The desired end product of urea cycle is urea. Urea in a pure state is white crystalline solid. It is the final nitrogenous breakdown product and is excreted from the body in urine. Its melting point is $133°\text{C}$. It is a colorless and odorless compound.

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.

Answer to Problem 15.75EP

Urea is a ${\text{N}}_{\text{2}}$ species.

Explanation of Solution

The structure of urea is:

The structure of urea suggests the presence of two ${\text{-NH}}_{\text{2}}$ groups in the structure thus it is characterized a ${\text{N}}_{\text{2}}$ species.

(d)

Interpretation Introduction

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

Concept introduction: Citrulline is a nonstandard amino acid and is an inetrmediate in the the urea cycle. It is encountered at step 2 of the urea cycle and undergo condensation reaction with aspartate to give 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.

Answer to Problem 15.75EP

Citrulline is a ${\text{N}}_{\text{3}}$ species.

Explanation of Solution

The structure of citrulline is:

Citrulline contains three nitrogen atoms and thus it is characterized as a ${\text{N}}_{\text{3}}$ species.