Direct Incorporation of Molecular Oxygen into Organic Material by Respiring Corn Seedlings.

Abstract

Etiolated corn (Zea mays) seedlings and homogenates were exposed for several hours to atmospheres containing nitrogen and oxygen enriched with Ol8. Chloroform-soluble substances recovered after exposure contained much larger amounts of 0*8 than did the residues from chloroform extraction. On the basis of this and additional supporting evidence, it was concluded that some of the O2 consumed by the seedlings during the respiratory process was incorporated directly into organic material through the agency of enzymes which catalyze the direct addition of molecular O2 to substrates. Lipoxidase is such an enzyme, and it was estimated that lipoxidase may participate to the extent of 0.4% in respiratory O2 absorption of 2.25-day etiolated corn seedlings.