### Liver Metabolism and Amino Acid Injection StudyThe diagram to the right displays experimental data from a study examining rat liver metabolism after amino acid injection. The study investigates:1. **N-acetyl-glutamate Content (Panel A)**: - **Description**: The graph in Panel A shows the N-acetyl-glutamate content in rat livers over time following an intraperitoneal injection of amino acids containing glutamate (1.5 g/kg body weight). - **Observation**: A decline is noted over time, indicating metabolic changes post-injection.2. **Carbamoyl Phosphate Synthetase I Activity (Panel B)**: - **Description**: The lower panel, Panel B, illustrates the activity of carbamoyl phosphate synthetase I (CPS I) in liver mitochondria with the same treatment conditions. - **Observation**: Similar to Panel A, a decrease in activity is observed over time.**Key Experimental Details**:- Data were consistent when L-glutamate alone was injected, rather than a mix of amino acids.- Levels of arginine and ornithine in the liver remained stable when arginine was not included in the injection.**Questions for Consideration**:(a) **Chemical Reaction Representation**: - Write out the structural formulas of reactions observed in each panel, including all reactants, enzymes, and cofactors. Ensure accurate representation of chiral centers.(b) **Significance of Coordinated Maxima**: - Analyze the implications of the synchronous peaks in both panels.(c) **Effect of L-Glutamate Injection**: - Discuss why L-glutamate alone produced similar results as the amino acid mixture injection.(d) **Stability of Arginine and Ornithine**: - Explain the biological rationale behind the constant levels of endogenous arginine and ornithine.This study provides insights into the metabolic processes following amino acid administration and the role of specific enzymes and compounds in liver function and regulation.

When amino acids are degraded in the tissue, they release ammonia. Ammonia is toxic to the cell so it is removed by adding it to glutamate to form glutamine.Glutamine synthase catalyses the addition of ammonia to glutamate to form glutamine.Glutamine is transported from the tissues to the liver where glutamate dehydrogenase removes the amino group from glutamine to form alpha-ketoglutarate (AKG). Ammonia is then eliminated via the urea cycle, illustrated below. N-acetyl glutamate synthase catalyses the formation of N-acetylglutamate from acetyl CoA and glutamate. N-acetylglutamate is the activator of carbamoyl phosphate synthase I. Carbamoyl phosphate synthase I catalyses the activation of free ammonia by converting it to carbamoyl phosphate in an ATP-dependent reaction. Carbamoyl phosphate donates the carbamoyl group to ornithine to form citrulline, an intermediate in urea cycle.From the reaction explained in step 2, it is evident that glutamate is metabolised into N-acetylglutamate that acts as an activator of carbamoyl phosphate synthase I. Other amino acids are metabolised to release ammonia that is used for carbamoyl phosphate synthesis. The coordinated maxima highlights the regulatory effect of n-acetylglutamate on carbamoyl phosphate synthase I and its overall effect as a stimulator of urea cycle. As n-acetylglutamate concentration in rat liver increases, so does the catalytic activity of carbamoyl phosphate synthase. L-Glutamate is the precursor of N acetylglutamate. N acetylglutamate activates carbamoyl phosphate synthase I. Amino acid oxidation yields ammonia, a substrate of CPS I.The response is similar in both cases because L-glutamate provides the substrate necessary for the synthesis of N-acetyl-glutamate. This, in turn, would activate CPSI, leading to increased carbamoyl phosphate synthesis and, eventually, enhanced urea cycle activity. Arginine is converted to citrulline in cytoplasm. Citrulline is transported to the mitochondrial matrix. In the mitochondrial matrix, citulline is converted to ornithine which is transported back to cytoplasm to regenerate arginine to produce urea.In the cycle illustrated step 1, we can see that the arginine's skeleton remains constant throughout. New molecules are added to it and lost without much change to the structure of arginine itself. Therefore, endogenous concentrations of arginine and ornithine remain constant. All the solutions are provided in the steps described above.