PURIFICATION AND CHARACTERIZATION OF RAT ADRENODOXIN

Adrenodoxin was purified from the rat adrenal gland. The A(414)A(280) value of the purified rat adrenodoxin was 0.90 and the oxidized spectr um showed absorption maxima at 320, 414 and 455 nm, similar to those o f bovine adrenodoxin. On SDS-PAGE, the rat adrenodoxin showed a single band with a molecular mass of 11.2 kDa, while the apparent molecular mass by gel filtration through Sephadex G-75 equilibrated with 10 mM K -phosphate (pH 7.5) was 27 kDa In the reconstituted system, V-max of N ADPH-cytochrome c reduction activity and the K-m for the rat adrenodox in were much the same as those for recombinant bovine adrenodoxin. In the case of cholesterol side-chain cleavage activity, however, these v alues of the rat adrenodoxin were about half of those of the bovine ad renodoxin. The CD spectrum of the rat adrenodoxin was similar to that of the bovine adrenodoxin but showed a significantly lower ellipticity value in the 195-205 nm region than that of the bovine adrenodoxin. T he structural differences may possibly explain differences in the enzy mic properties between rat and bovine adrenodoxins.