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Thesis - Open Access

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Master of Science (MS)

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The pathway of the nitrogen atom after the initial nitrogen fixation reaction has taken place is not known. This study is an attempt to learn something about the enzymes that are involved in amino acid synthesis. The cell has varying demands for the intermediary metabolites of nitrogen, as the processes of protein and other polymer synthesis vary. In addition, the cell is often confronted with changing supplies of nitrogen and energy, as a function of environmental change. Efficient growth depends upon the optimum utilization of metabolites in response to variation in cellular needs. The bacterium Klebsiella pneumoniae not only has the ability to adapt itself by utilizing various kinds of nitrogen compounds, but also fixes gaseous nitrogen under anaerobic conditions, when other nitrogen compounds are not available. Unless some of the organic substances such as amino acids can pass directly into the cell and go to the amino acid pool immediately, most nitrogen materials must be reduced or deaminated to ammonia before they can be incorporated into amino acids. Two kinds of enzymes responsible for ammonia assimilation found in most organisms are glutamate dehydrogenase and glutamine synthetase. These enzymes are also found in Klebsiella pneumoniae. It is interesting that the activity of glutamate dehydrogenase of N2 grown Klebsiella pneumoniae seems too low to tell if it is responsible for ammonia assimilation. Therefore, attempts to find other enzymes have been made. A new enzyme glutamine: 2-oxoglutarate amidotransferase (NADP oxidoreductase) was found recently, which catalyzes the reaction by transferring the terminal amino group from glutamine to ketoglutarate resulting in the formation of two moles of glutamic acid. This glutamic acid is ready for either amination or transamination. Thus, the transamination from glutamine or glutamic acid to other ketoacids may also be important in directing ammonia assimilation. Because glutamate dehydrogenase, glutamine synthetase, amino- and amido-transferase are interrelated, their relationships under different growing conditions will be different. The object of this study is trying to find these relationships which are still unknown in Klebsiella pneumoniae.

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South Dakota State University