Metabolic Pathways of Bacterial Nitrification 



403 



o 



— 19.5 

 K 



O 15.0 



I .5 - 



TUBE NO. 20 40 60 

 .005 N Hcl 



110 130 150 170 285 306 363 



.01 N Hcl .20 N Nad 



Fig. 4. Demonstration of ATP formation concomitant to nitrite oxidation 

 by partially pmified nitrite oxidase, using column chromatographic pro- 

 cedure. 



substrate, nitrite, a suitable phosphate acceptor (ADP), or a 

 hexokinase trapping system when catalytic quantities of ADP 

 are used (Table 1). That ATP is the phosphorylation product, 

 was confirmed by the separation of ADP and ATP from a com- 

 plete nitrite oxidase reaction mixtiue ( containing substrate quan- 

 tities of ADP and no hexokinase system) by established ion ex- 

 change chromatography (Fig. 4), and paper chromatography 

 procedures (6). Most of the P^^ was incorporated into the ATP 

 fraction and the remainder in the ADP. Nitrite oxidase particles 

 possess ATP-ase, myokinase, and ATP-ADP exchange activities 

 but did not exhibit any ATP-P^^ exchange reaction.* According 

 to the studies of the authors, the phosphorylation was not un- 

 coupled by 2,4,dinitrophenol, L-th.yroxin, dicumarol, etc. (6). 

 The recent preliminary report by Malavolta et ah (31) also indi- 



unpublished data. 



