126 PLANT RESPIRATION 



to CO2 a single plant substance with the aid of oxidising 

 enzymes of plants furnished great difficulties to each theory that 

 stood for a participation of peroxidase in the respiratory process. 

 Bertrand, Portier and Porodko^ each claimed that the oxidising 

 enzymes of plants have nothing to do with respiration because 

 they are entirely unable to attack the respiratory material. 

 Several other investigators have followed this suggestion. 

 Kostychev's experiments showed that CO2 is liberated in 

 abundance when the system, peroxidase + H2O2, acts on fer- 

 mented sugar solutions. The same system — peroxidase + 

 H2O2 — is entirely unable to decompose dissolved sugar to 

 form COo. In this way for the first time plant substances {the 

 chemical nature of which is by no means established) have been 

 successfully oxidised to CO2 with the aid of peroxidase outside the 

 living cell,'' and the participation of peroxidase in the respiratory 

 process been made plausible. It is very evident that this result 

 favors the theory of connection of alcoholic fermentation with 

 oxygen respiration. Whether one traces, with Meyerhof, the 



'Bertrand, G. Compt. rend. 122: 1132. 1896; Portier. Les oxydases dans la sene 

 animale. 1897; Porodko. Beih. z. Hot. Centralbl. 16: i. 1904. 



*■' By the use of a mixture of neutral sodiuin_(or potassium) phosphate solution 

 and an aqueous extract of oxidase from potato tubers, Lyon (Harvard thesis. 

 1926; Amer. Jour. Bot. 14: 274-283, 1927) was able to effect a slow 

 oxidation of glucose or fructose with the liberation of CO2. Together with a 

 demonstration of the increased rate of production of CO2 when such phosphate 

 solutions were applied to Elodea, wheat seedlings or Spirogyra (J. Gen. Physiol. 

 6: 299-306. 1923-24), these experiments constitute the basis of a claim that 

 the phosphate ion exerts a promoter action on the oxidases. A more exact 

 analysis of the relationship showed that for the COo-production bj- Elodea the 

 effect could be expressed by the equation 



(CO2 - 62.475) (pPOj - 2.13) = 114.43, 

 which was described in a footnote on page 21. A similar analysis of the pub- 

 lished data of other workers indicated that the phosphate ion exerts the same 

 effect on other enzymes including peroxidase (Smimow, A. J. Biochem. Z. 

 155: 1-33. 1925) and pancreatic lipase (Piatt and Dawson. Biochem. Jour. 

 19: 860-874. 1925; and other workers). The same hyperbolic relationship to 

 phosphate ion concentration, expressed by the equation 



(Activity of Enzyme) (pPOO" = K 

 where n and A' are constants and n varies from one to six under different condi- 

 tions, appears to hold. 



This relationship of phosphate to respiration may be related to the problem 

 of the connection between lipoids and respiration which is discussed by Palladin 

 (Plant Phj-siology. Trans, by Livingston. 3rd. ed. pp. 186-188). — Ed. 



