BIOCHEMICAL AND SPECTROSCOPIC PROPERTIES OF THE 4-SUBUNIT QUINOL OXIDASE (CYTOCHROME BA(3)) FROM PARACOCCUS-DENITRIFICANS

The ba(3) quinol oxidase from Paracoccus denitrificans has been purifi ed by a new protocol leading to significantly higher yields than previ ously reported (Richter et al. (1994) J. Biol. Chem. 269, 23079-23086) . In an SDS PAG an additional protein band compared with the previous preparation appears, which can be identified as the major form of subu nit II. All protein bands can be assigned to genes of the qox operon b y N-terminal sequencing, indicating that the oxidase consists of four subunits. In addition to one heme A, one heme B, and one copper atom, the preparation contains two ubiquinone molecules per enzyme. The oxid ase is further characterized by electron paramagnetic resonance (EPR), circular dichroism (CD) and magnetic circular dichroism (MCD) spectro scopy.