596 G. SCHMIDT 



an example of phylogenetic changes in the pattern of certain metaboHc 

 pathways. 



b. Adenyl Deaminase of Aspergillus Oryzae 



Mitchell and McElroy found in 1946 that takadiastase contains an en- 

 zyme capable of deaminating adenosine.^®" They succeeded in separating 

 taka-adenosine deaminase from some contaminating enzymes on a chro- 

 matopile in quantities suitable for isolation experiments.^®^ Kaplan, Colo- 

 wick, and Ciotti^®' achieved a considerable further purification of the en- 

 zyme by acetone-alcohol and ammonium sulfate fractionations with the 

 practically complete removal of phosphatases. According to Kaplan et al}^- 

 adenosine, adenosine-5'-phosphate, adenosine-3'-phosphate, ATP, ADP, 

 oxidized and reduced DPN, and adenosine-diphosphate-ribose are deami- 

 nated by the purified enzyme at rates decreasing in this order. Adenine, 

 adenosine-2'-phosphate and TPN are not deaminated. 



The lack of specificity of the Aspergillus oryzae adenyl deaminase is in 

 remarkable contrast to the highly selective action of animal adenyl de- 

 aminases. The deamination of DPN with preservation of the pyrophosphate 

 bond represents the first example of the enzymic deamination of an adenyl 

 compound of a pyrophosphoryl dinucleotide. 



pH Optimum. Aspergillus oryzae deaminase has a broad zone of optimal 

 activity between pH 5 and pH 8. 



Michaelis-Menten Constants. The following K values were calculated for 

 the various substrates by Kaplan et al.:^^'- adenosine, 0.6 X 10"^ M; ADP, 

 0.7 X 10-3 M; 5'-AMP 0.8 X IQ-^ M; ATP, 1.2 X 10-^ M; adenosine- 

 diphosphate-ribose 1.5 X IQr' M; 3'-AMP, 1.7 X 10"^ M. 



c. Adenosine Deaminase 



Most tissues (intestines, liver, kidney, spleen, brain, striated muscle, 

 heart) of higher animals contain adenosine deaminase in very active con- 

 centrations. The enzyme was discovered by Gyorgy and Rothler;^®^ the 

 high degree of its specificity was recognized by Schmidt^®^ in an investiga- 

 tion on muscle deaminases, and its distribution in animal tissues was de- 

 scribed by Conway and Cooke. ^^^ Procedures for its partial purification 



160 H. K. Mitchell and W. D. McElroy, Arch. Biochem. 10, 351 (1946). 



i«i H. K. Mitchell, M. Gordon, and F. A. Haskins, J. Biol. Chem. 180, 1071 (1949). 



'62 N. O. Kaplan, S. P. Colowick, and M. M. Ciotti, J. Biol. Chem. 194, 579 (1952). 



1" P. Gyorgy and H. Rothler, Biochem. Z. 187, 194 (1927). 



i«^ G. Schmidt, Z. physiol. Chem. 179, 243 (1928). 



1" E. J. Conway and R. Cooke, Biochem. J. 33, 479 (1939). 



