494 



Studies on the Reductase of Liver and Kidney. 



Methaemoglobin is by press juice reduced at body temperature to haemoglobin 

 after the manner of non-living, reducing agents. Such a relatively stable 

 compound as sodium nitrate is reduced to nitrite, and ferric chloride to the 

 ferrous condition. These reductions are not due to the proteins of the 

 juices, since a control of boiled juice alters none of the substances hitherto 

 used to demonstrate reduction. We intend to use the nitrate reaction as a 

 basis of a method to follow these reduction chauges quantitatively. 



3. The probability of the enzymic character of tissue reduction is further 

 confirmed by the effect of certain protoplasmic poisons lately investigated by 

 one of us.* Certain virulent protoplasmic poisons inhibit reductase in virtue 

 of their acidity rather than through their toxicity ; this finding is in accord 

 with the well established fact that acidity (concentration of H-ions) inhibits 

 the activity of many enzymes. 



4. Though the presence of proteins in press juice is not responsible for 

 such a reduction as that of soluble Prussian blue to the colourless condition, 

 yet the proteins of the juice form with the pigment a colourless chemical or 

 physical compound. This change takes place rapidly at 100° C. and exceed- 

 ingly slowly at room temperature. 



One of usf has shown that such proteins as egg-albumin and gelatine 

 readily form with soluble Prussian blue such compounds at higher temperatures. 

 It would be convenient to allude to these phenomena as the " Creighton 

 effect." We desire to distinguish this fading of pigments through combina- 

 tion with proteins from true vital reduction, and we venture to suggest that 

 the so-called reduction effected by colloids and studied by HeffterJ may be 

 of the nature of the fading of pigments ; it is not the same phenomenon 

 as the reduction which we are studying. 



5. We lay a considerable degree of stress on the fact that reductase is able 

 to reduce chemical substances differing very widely in structure, propensities 

 and stability. Not only can it reduce compounds containing oxygen such as 

 methaemoglobin and sodium nitrate, but with equal potency substances 

 which contain no oxygen and are of a relatively stable nature, such as ferric 

 chloride and soluble Prussian blue. 



The expenses of this work were met by a grant to one of us (D. F. H.) 

 from the Government Grant Committee, which is hereby gratefully 

 acknowledged. 



* Harris, D. Eraser, ' Bio-Chem. Jonrn.,' vol. 6, p. 2. 



t Creighton, H. J. M., 'Trans. Nova Scotia Inst. Sci.,' 1911—1912, vol. 13 (2), 

 pp. 61—75. 



X Heffter, A., ' Medizinisch-Naturwissenschaftliches Archiv,' vol. 1, Part 1, p. 81 ; also 

 4 Archiv f. expr. Path, und Pharm.— Festschrift f. O. Schmiedeberg,' 1908, p. 253. 



