no 



R. MAMELAK, J. H. OUASTEL 



VOL. 12 (1953) 



pyruvate, brings about reduction of pyruvate in presence of lactic dehydrogenase, and 

 the regenerated DPN becomes available for further oxidation of the pyruvate. 



TABLE VI 



EFFECT OF DPN ON SODIUM PYRUVATE BREAKDOWN IN PRESENCE OF EXTRACTS OF CI. SpOfOgeneS 



Warburg manometer vessels contained i ml cell-free CI. sporogenes extract in i % sodium thio- 

 glycollate + 0.002 M phosphate. 0.02S M NaHC03 present. Gas = 93% N2 + 7% COg. Total vol. 

 3.2 ml. Temp. 37°. 



Expt. 



Contents of vessel 



UM CO. ^'f Py^'^'^'f flM Lactate 

 r^ " disappeared formed 



1 (105 min) No substrate + 3 mg DPN 1.6 



0.02 M Pyruvate g.6 



0.02 M Pyruvate + 3 mg DPN 18.5 



2 (70 min) o.oi M Pyruvate + 3 mg DPN + Brain homogenate 21.5 



o.oi M Pyruvate + 3 mg DPN + Brain homogenate, 



no bacterial extract present 5.0 



19-5 

 41.0 



12.2 



2.4 



Lactate formation from alanine in presence of CI. sporogenes and lactic dehydrogenase, 

 DPN, and arsenite 



The fact that an alanine-proline mixture gives rise, in presence of CI. sporogenes 

 and lactic dehydrogenase, to lactate when proline reductase is inhibited by the addition 

 of arsenite is shown in the results given in Table VII. Arsenite (0.005 M) almost com- 

 pletely eliminates carbon dioxide and ammonia formation from a mixture of alanine 

 and proline in presence of an extract of CI. sporogenes. When a brain homogenate is 

 added to such an arsenite-inhibited system the rate of lactic acid formation is almost 

 identical with that obtained in the absence of arsenite, whilst that of ammonia formation 

 is greatly increased. Approximately equimolecular quantities of lactic acid and ammonia 

 are produced (Table VII). These results are those expected if arsenite inhibits the proline 

 reductase with relatively little effect on the following systems : 



Alanine + DPN + HgO = Pyruvate -^ NH3 + DPNHg 



CI. sporogenes 



Pyruvate + DPNH2 = Lactate + DPN 



Lactic 



Dehydrogenase 



TABLE VII 



EFFECT OF ARSENITE ON AMINO ACID INTERACTION IN EXTRACTS OF CI. SpOVOgeneS 



Warburg manometer vessels contained i ml cell-free CI. sporogenes extract (in i % thioglycoUate 

 and 0.002 M phosphate) ; 0.028 M NaHCO., present. Amino acids = 0.02 M L-form. DPN = 3 

 mg/vessel. Sodium arsenite = 0.005 M . 0.5 ml Brain (rat) homogenate (i % nicotinamide and 0.002 M 

 phosphate). Gas = 93% Ng + 7% COg. Total vol. 3.2 ml. Time 100'. Temp. 37°. 



Contents of vessel 



fl.M CO. /(M A7/3 jtiM Lactate 



Bacterial Extract 



Alanine -|- Proline -|- Bact. Extr. 



Alanine + Prohne -|- Bact. Extr. + Arsenite 



Bacterial Extr. -\- Brain homog. 



Alanine -|- Proline -(- Brain homog. 



Alanine -|- Proline -\- Bact. Extr. + Brain homog. 



Alanine + Proline -f- Bact. Extr. + iirain homog. -\- Arsenite 



3-2 



32.0 



4-7 

 10.4 



3-8 



38.0 



8.0 



7-1 

 395 

 10.0 

 14.0 



3-8 



46-5 

 22.5 



<i.o 



1.8 

 2.0 

 2.7 



<I.O 



12.5 



12.0 



References p. 120. 



