Abstract
The method employed in these investigations was that reported by one of us. 1 Kidney, liver, heart and skeletal muscles were used. The last two named tissues were practically free from blood. Small amounts of connective tissues were always present, but were eliminated when possible from the test material, as they have practically no oxidizing power. The velocity of the oxidation, as indicated by the quantity of indophenol formed, was determined for tissue previously minced without sand, and tissue ground with an equal volume of quartz sand for exactly 10 minutes. In neither case were the particles of tissue more than 0.5 mm. in thickness. Determinations were made at a temperature of approximately 23° C.
The curves in the accompanying figure represent the velocity of oxidation with tissue ground with sand, and differ from those obtained from minced tissue in being steeper, and running to completion earlier. These curves have been corrected for spontaneous oxidation according to the method described. 1 In either case there is a marked difference in the power of the various tissues studied to
form indophenol. In no instance did the rate of oxidation and the time show an exact linear relationship, although in some individual experiments, particularly skeletal muscle minced without sand, an exact linear proportionality existed. In all of our experiments the curves of oxidation were almost exactly linear for a time. The deviation, which represented a diminution in the oxidation velocity, became progressively greater, until finally an equilibrium was reached. This state was not always maintained, but frequently dropped, as in the case of kidney shown in the figure. This suggests that a reductase may also be present. These observations lead us to agree with Vernon 2 that there is an excess of substrate present during the initial stages of the reaction so that an optimal contact between tissue and substrate is insured.
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