232 



MARTIN KLINGENBERG 



TABLE II 



Redox State of Pyridine Nucleotides in Skeletal Muscle Mitochondria 



Additions 



DPNH 



/xMol/g.Prot. 



TPNH 

 /xMol/g.Prot. 



DPNH 

 ^DPN* 



Glycerol- 1 -P 

 Glycerol- 1 -P + ATP 

 Succinate 

 Succinate + ATP 

 Pyruvate + malate 



0-72 

 2-05 

 030 



1-85 

 I -So 



0-47 

 0-58 

 0-39 

 o-6o 

 o-SS 



o- 17 

 0-47 

 o-o8 

 0-44 

 032 



Mitochondria after washing with serum albumin 



Glycerol- 1 -P 2-02 044 042 



Succinate 3* 01 0-46 063 



Pyruvate + malate 2-28 0'44 0-48 



Incubated in 03 M sucrose, 10 mM triethanolamine-HCl-bufFer, i mM EDTA, 

 pH 72, 25°. Concentration of substrates: 4 mM; ATP: i mM. 



*i;DPN = DPN + DPNH. 



isolated from some other organs. The second part of Table II shows 

 that, after washing the skeletal-muscle mitochondria with serum albu- 

 min, no ATP is required for DPN reduction. When added after the sub- 

 strates, albumin is also effective in facilitating the DPN reduction, as 

 shown in Fig. 3. It is assumed that albumin reverses an endogenous 



DPN 

 reduction 



Fig. 3. The effect of serum albumin, antimycin A and ATP on the redox state 

 of the mitochondrial DPN in the presence of glycerol- 1 -phosphate. The absorption 

 trace (dashed curve) is corrected for the absorption due to albumin and by a shift 

 of the pen position, for the absorption due to antimycin A (cf. legend Fig. 2.). 



