Ammonia Glutamine

Ammonia transport in the blood from the peripheral tissues to the liver occurs by two major mechanisms glutamine can be synthesized from glutamate and ammonia (glutamine synthetase) or pyruvate can be transaminated to alanine. In the liver, the ammonia group is removed from glutamine by glutaminase and from alanine by transamination. 

Glutamate + ATP + ammonia = glutamine + ADP + Pj The transposed stoichiometric number matrix for this reaction is... 

In writing out the conservation matrix for this biochemical reaction, the reactants are arbitrarily taken in the order glutamate, atp, pi, ammonia, glutamine, and adp. The elements are taken in the order C, O, N, and P. These elements introduce the following constraints ... 

It is of interest to note that this row reduced conservation matrix is characteristic of all biochemical reactions of the form A + B + C = D + E + F. The last column indicates that adp = glutamate + atp - pi + ammonia - glutamine, which is equation 7.4-4. 

Now the question is "What constraint has to be added to conmat to produce this row reduced conservation matrix " There is no single answer, but the constraint has to tie together the two reactions indicated by conmat. We can imagine these are atp + h2o = adp + pi and glutamate + ammonia = glutamine + h2o. One possible additional conservation equation is... 

Ligase reactions necessarily involve coupling. As a first example, consider reaction 6.3.1.2 glutamate + atp + ammonia = glutamine + adp + pi (All-1)... 

Scores of chemical compounds have been identified in unbumed tobacco. Basically it is cellulose. The cured product contains acids (citric, oxalic, formic), alkaloids (nicotine, anabasine, myosmine), and carbohydrates (lignin, pentosans, starch, sucrose), as well as tannin, ammonia, glutamine, and micro amounts of zinc, iodine, copper, manganese, and polonium-210. See cigarette tar smoke (4). 

A second major method of generating ammonia in the liver and kidney is via glutaminase, which catalyzes the hydrolysis of the amino-acid glutamine to form glutamate and ammonia. Glutamine is one of the amino acids that... 

K m values (mM) pH optima Ratio ammonia glutamine activity Action of asparagine ... 

Automated ammo acid analysis of peptides containing asparagine (Asn) and glutamine (Gin) residues gives a peak corresponding to ammonia Why" ... 

The 7 glutamyl phosphate formed m this step is a mixed anhydride of glutamic acid and phosphoric acid It is activated toward nucleophilic acyl substitution and gives glutamine when attacked by ammonia... 

Although the antibacterial and antifungal activities of bialaphos and phosphinothricin were not found to be usehil, the two agents were later used as biodegradeable, relatively nonselective, postemergent herbicides. Glutamine synthetase inhibition is toxic to plants because the enzyme is key to ammonia assimilation. There is some selectivity for individual plant species as shown by the LD for bialaphos ranging from 0.125 to 8.5 kg/ha (301—303). 

Both threo- (14) and eo f >"4-fluoro-DL-glutamic acid (/5) are noncompetitive inhibitors of glutamine synthase, an enzyme that catalyzes the synthesis of glutamine from L-glutamic acid and ammonia. This mhibibon may explain the... 

Ammonia is accepted by glutamic acid in an energy (ATP consuming) step, and converted to glutamine. This reaction is catalysed by glutamate synthetase (GS) and can be written as ... 

Stress is a broad term often used with animal cells. Frequently mechanical forces are meant using this term but chemical stress is also important cultivating animal cells. The chemical environment of the cell in a reactor have to be considered very carefully. The complexity of the medium requirements and the metabolic pathway cause very often growth limitations. Studying these limitations in order to find the reasons showed to be difficulty because of the complexity of the system. Nevertheless, glucose, glutamine, lactate and ammonia are found to be critical parameter as well as the osmotic pressure. 

Glutamine as an important source for the synthesis of purines, pyrimidines and amino sugars is essential for most cell lines, too. High concentrations of glutamine may also effect cell growth indirectly as the major end-products are lactate and ammonia [15]. Both known to be toxic metabohtes. 

Another toxic metabolite is ammonia. It is released by spontaneous decomposition of glutamine and to a far greater extend produced as a metabolite in... 

While ammonia, derived mainly from the a-amino nitrogen of amino acids, is highly toxic, tissues convert ammonia to the amide nitrogen of nontoxic glutamine. Subsequent deamination of glutamine in the liver releases ammonia, which is then converted to nontoxic urea. If liver function is compromised, as in cirrhosis or hepatitis, elevated blood ammonia levels generate clinical signs and symptoms. Rare metabolic disorders involve each of the five urea cycle enzymes. 

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