Studies on the electron transport system: III. The properties of two modified forms of ETP

Abstract

Some enzymic properties and the composition of two modified forms (I and II) of the electron transport particle (ETP) have been examined. Such preparations contain per mg of protein 0.42·10 −3 μmole of flavin, 2.5·10 −3 μmoles of heme, 6.2·10 −3 μmoles of non-heme iron and 2.4·10 −3 μmoles of copper—the molecular or atomic ratios being in round numbers 1:6:15:6. The antimycin titer of the preparations was 0.5·10 −3 μmole/mg. The oxido-reduction of the prosthetic hemes in presence of DPNH and oxygen has been demonstrated. Heme reduction was partially inhibited by antimycin. The absorption spectrum of the enzyme indicates the presence of at least two groups of hemes—one group with bands at 563, 554, 535 and 525 mμ—the other with a band at 603 mμ.