. Biological structure and function; proceedings. Biochemistry; Cytology. INTEGRATED OXIDATIONS IN ISOLATED MITOCHONDRIA 79 in the vicinity of the succinate dehydrogenase and that intact mitochondria are relatively impermeable to oxaloacetate. With particulate preparations derived from liver mitochondria by lysis with phosphate and washing with KCl [13] and from kidney by the method of Slater [14], concentrations of oxaloacetate of the order of 10 juM had a profound inhibitory action on succinate oxidation. With these preparations permeability effects would be expected to be far less pro- noun
. Biological structure and function; proceedings. Biochemistry; Cytology. INTEGRATED OXIDATIONS IN ISOLATED MITOCHONDRIA 79 in the vicinity of the succinate dehydrogenase and that intact mitochondria are relatively impermeable to oxaloacetate. With particulate preparations derived from liver mitochondria by lysis with phosphate and washing with KCl [13] and from kidney by the method of Slater [14], concentrations of oxaloacetate of the order of 10 juM had a profound inhibitory action on succinate oxidation. With these preparations permeability effects would be expected to be far less pro- nounced. However the order of addition of substrate and inhibitor had a Kp Kp OAA 100 n-7 -t :. ^P i^P Malonate T T. 0 12 3 4 5 Time (mm) Fig. 9. Effect of oxaloacetate (12-5 /^m) and malonate (125 /<m) on the oxida- tion of succinate (10 niM) by a Slater kidney preparation. The medium contained 20 mM tris, pH 7 45. marked effect on the inhibition of oxygen uptake. This is illustrated for a kidney preparation in Fig. 9. If 10 to 50 /xM oxaloacetate were added before the succinate, no oxygen uptake occurred for approximately i min., after which the steady-state of inhibited respiration was observed. On the other hand, when the oxaloacetate was added after the succinate several minutes elapsed before the steady-state was established. In the latter case, the lower the oxaloacetate concentration the longer was the time taken before the final rate was observed. In contrast the order of addition of sub- strate and inhibitor was unimportant when malonate and pyrophosphate were Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original IUB/IUBS International Symposium (1st : 1960 : Stockholm); International Union of Biochemistry; International Union of Biological Sciences; Goodwin, T. W. (Trevor Walworth); Lindberg, Olov
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