Utilization of ammonia

H2. Hankins, J., Bessman, S. P., Esmond, W., Mansberger, A., and Cowley, R. A., Origin and utilization of ammonia in shock. Submitted to Intern. Soc. Surg., Mexico City, October 1957. 

Vitti, T.G., R.Vukmirovich, and O.H.Gaebler. 1964. Utilization of ammonia nitrogen, administered by intragastric, intraperitoneal, and subcutaneous routes effects on growth hormone. Arch. Biochim. Biophys. 106 475-482. 

The utilization of ammonia resulting from the combination of carbamyl phosphate with aspartic acid, the initial reaction for the synthesis of the pyrimidine nucleotides, continues only as long as there is a requirement for them (Fig. 3). Regulation of this biosynthetic pathway is probably by way of feedback inhibition of aspartate transcarbamylase. The rat liver enzyme is inhibited by uridine, cytidine or thymidine or such derivatives as CMP, UTP, or TMP, all intermediates or products of this pathway (B8). This is not the only enzyme of the pathway which may be subject to feedback regulation. Dihydroorotase from rat liver is also inhibited by some pyrimidines and purines (B9). 

Ma Q, Peng R, Tian L, Meng G (2006) Direct utilization of ammonia in intermediate-temperature sohd oxide fuel cells , Electrochem. Commun., 8, 1791-1795. 

See also Utilization of Ammonia, Transamination in Amino Acid Metabolism... 

See also Urea Cycle Reactions, Urea, Uric Acid, The Nitrogen Cycle, Utilization of Ammonia, Metabolic Nitrogen Balance, Amino Acid Degradation, Ammonia Transport in the Body, Citric Acid Cycle, ATP as Free Energy Currency (from Chapter 12)... 

See also Table 5.1, Amino Acids, Genetic Code, Transamination in Amino Acid Metabolism (from Chapter 20), Utilization of Ammonia (from Chapter 20), Transamination of Citric Acid Cycle Intermediates, Essential Amino Acids... 

See also Urea Cycle Descriptions, Urea Cycle Reactions, Utilization of Ammonia, Uric Acid, Purine Degradation... 

See also The Nitrogen Cycle, Utilization of Ammonia, Urea Cycle... 

See also The Nitrogen Cycle, Nitrogen Fixation, Utilization of Ammonia, Dimethylsulfoxide Reductase, Nitrite Reductase, Siroheme, Ferredoxin, Figure 20.2... 

Utilization of Ammonia Biogenesis of Organic Nitrogen (Figure 20.7)... 

Guanine formation occurs following oxidation in position 2, to form xanthylic acid." This oxidation has been demonstrated with a DPN-requiring enzyme from bone marrow. Subsequent animation occurs through different mechanisms in animal and bacterial systems. In bone marrow extracts the amide of glutamine is transferred, while in bacterial extracts ammonia is utilized more readily than glutamine. The utilization of ammonia by the bacterial system is accompanied by the hydrolysis of ATP to AMP and PP. In addition to these reactions, it is known that adenine and guanine can be interconverted, but the enzymatic mechanisms are not known. 

If high-energy feeds are not provided, full utilization of ammonia is not obtained. 

The ammonia concentration is known to be low in liver (408, 409). However, as pointed out previously, the ammonia K value for carbamyl phosphate synthetase is influenced favorably by the presence of K+, a situation which would obtain in the cell. Further, the irreversibility of the over-all carbamyl phosphate synthetase system serves to insure efficient conversion of very low concentrations of ammonia. As a matter of fact, in the presence of a medium in which potassium is the major cation, effident utilization of ammonia at a concentration of the order of 10 M is realized (406). 

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