232 GEORGE H. HOGEBOOM AND WALTER C. SCHNEIDER 



ponent (S = 6.3). Although the latter protein has not as yet been obtained 

 in a pure state, its behavior on fractionation and the finding that it is 

 precipitated on dialysis against water suggest that it is a type of globulin. 

 Of some interest is the finding that it could not be detected in preparations 

 obtained from the mitochondria of a liver tumor. ^^ 



Fig. IB shows the sedimentation pattern of a fraction obtained from the 

 mitochondrial proteins by precipitation with 25% ethanol at pH 6.0 and 

 then reprecipitation between 35 and 50% saturation with ammonium 

 sulfate. It can be seen that the main component {S = 6.3) is concentrated 

 to a considerable extent. Since this fraction, like the original preparation, 

 was highly colored and apparently included a heme-containing protein (as 

 indicated by a pronounced absorption peak at 410 m;u), it was desirable 

 to determine what components absorbed light at this wavelength. Ac- 

 cordingly, the photographs of Fig. IB were taken with an interference 

 filter that isolated the mercury arc spectral band at 405 mju. It can be seen 

 that practically all the absorbing material was associated with the small, 

 rapidly sedimenting peak {S = ca. 12). It may be mentioned that this 

 component sediments at approximately the same rate as do purified prep- 

 arations of catalse (cf. footnote 173). 



When disruption of liver mitochondria was accomplished by forcing the 

 particles through a small orifice under high pressure, ^^ the protein was 

 strikingly different from that of Fig. lA. Components, usually polydisperse, 

 with sedimentation constants of 4.0, 5.1, 7.5, and 12 were visible, but the 

 main component of Fig. lA {S =_ 6.3) could not be seen. The results of 

 additional experiments (unpublished) have suggested that the latter pro- 

 tein is either denatured or altered in some other way when the mitochondria 

 are forced through an orifice. 



Damage to the mitochondrial membrane either by the above two pro- 

 cedures, by the action of the Waring Blendor, or by lysis of the particles 

 on exposure to distilled water, results in the release of several enzymes into 

 solution. These include acid phosphatase,^^* adenylate kinase,^"* -^'^ glutamic 

 dehydrogenase,*^ fumarase,^" ribonuclease,^^ and deoxyribonuclease.^^ The 

 experiments of de Duve et al} and Berthet and de Duve^-* are of particular 

 interest in this respect. These investigators found that the acid phosphatase 

 of liver mitochondria is inactive when the particles are intact but is ren- 

 dered highly active by damage to the mitochondrial membrane. These and 

 additional experiments indicated that the membrane is relatively imper- 

 meable to the substrate, |S-glycerophosphate, and that acid phosphatase 

 is probably present in a diffusible state within the particles. An almost 

 identical situation was found by the writers to hold for glutamic dehy- 

 drogenase.*^ 



1" K. Agner, Biochem. J. 32, 1702 (1938). 



