Studies on the enzymatic deamination of D-alpha-amino acids


In the world of living organisms there are thousands of separate and individual chemical reactions taking place in the course of their intermediary metabolism. These reactions are catalyzed by complex organic catalysts known as enzymes. One such reaction involves the deamination of amino acids in order that these amino acids may be used as fuel. This reaction takes place according to the equation [--see thesis for equation--] and is catalyzed by the enzyme amino acid oxidase. Most of the natural occuring amino acids belong to the 1 series. However, in the body there are found 1-amino acid oxidases and d-amino acid axidases both of which are stereo-specific and are without effect upon the amino acid of opposite stereochemical configurations of the two such groups of enzymes found in mammals the group which is by far the most active is the d-amino acid oxidase. These enzymes are capable of performing their catalytic activity outside of the cell which produce them. In studying the activity of various tissues for oxidase activity it is, therefore, common practice to separate the tissue from the animal, masserate the tissue to destroy all the cells and extract the enzymes from the masserated tissue. To such extract the individual amino acid may be added the oxidative deaminase observed in vitro. One of the difficulties in such experimentation consists in the measurement of the rate and extent of the reaction. This has previously been done by measuring the rate and extent of oxygen consumed or the rate and extent of the keto-acid production. Both of these methods present inherent weaknesses which make them unsuitable for accurate and extensive work. It was believed that a measure of the rate of ammonia production would be more accurate and a much easier determination to perform than either of the other two. It was toward this end that the research of this thesis was directed. By using the rabbit kidney tissue and various d-amino acids it was shown that deamination of these amino acids as measured by the rate fo ammonia production followed the same general pattern as reported by Krebs and his contemporaries as measured by oxygen consumption and keto-acid production. The ammonia thus produced was easily and accurately measured with Nessler's reagent by a photoelectric colorimeter. The tissue from several other rabbit organs were also examined for d-amino acid oxidase activity and considerable variation of such activity was shown in the study.



College and Department

Physical and Mathematical Sciences; Chemistry and Biochemistry


Date Submitted


Document Type




Amino acids



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