146 LARS ERNSTER 



TABLE V 



Properties of DPNH Oxidase Activity of Liver Mitochondrial 

 Fragments Prepared According to Kielley and Kielley (1953) 



(Ernster, Danielson and Conover, unpublished) 



The test system contained submitochondrial particles ("light pellet") from 

 200 mg. liver, o-i mM DPNH, 0-02 m phosphate buffer, pH 7-5, and where 

 indicated, i mivi amytal, o-8 jug./ml- antimycin A, 0-33 mivi KCN, o-oi mM 

 cytochrome c, in a final volume of 3 ml. The oxidation of DPNH was followed at 

 340 m/Li in a recording Beckman DK2 spectrophotometer. 



Fig. 4. Requirement of DT diaphorase for the vitamin Kj-mediated oxidation 

 of DPNH by mitochondrial fragments in presence of amytal (Conover and 

 Ernster, unpublished). The medium contained 19 /nmoles orthophosphate (pH 7-5) 

 and 2 mg. serum albumin in i -o ml. Submitochondrial fragment preparation from 

 I g. of rat liver was used. The amounts of the additions were as follows: i-o 

 /xmole DPNH, 2-0 /^moles amytal, 0005 jumole vitamin K3, purified DT diaphor- 

 ase capable of reducing i /imole DCPIP per min., and 003 /imole dicoumarol. 

 Final volume, i -3 ml. Temperature, 20 . 



the by-pass could be achieved by adding a purified sample of DT 

 diaphorase. 



QUINONE SPECIFICITY 



These early studies were carried out using vitamin K3 as the only 

 quinone. Then Dr. Conover made the somewhat surprising observation 

 that, although DT diaphorase can react with a number of both naphtho- 



