| Abstrakt: |
DPNH-rubredoxin reductase, a flavoprotein which functions as an electron carrier in an enzyme system from Pseudomonas oleovoranscapable of hydroxylating fatty acids and hydrocarbons, has been isolated in homogeneous form. The apparent molecular weight is 55,000 as judged by sedimentation and diffusion measurements; a similar result was obtained by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate and mercaptoethanol, thereby suggesting the presence of a single polypeptide chain. FAD was identified as the prosthetic group and was shown to be present in the amount of 1 mole per mole of enzyme. The oxidized protein has absorption maxima at 450, 378, and 272 nm, with an A272:A450ratio of 6.6 and a molar extinction coefficient at 450 nm of 11.0 x103. The spectrum is that of a flavoprotein apparently free of other prosthetic groups. Metals could not be detected by atomic absorption spectrophotometry. The amino acid composition shows a high content of hydrophobic residues, particularly leucine, isoleucine, and valine. The purified enzyme catalyzes the rubredoxin-dependent reduction of cytochrome cin the presence of DPNH and also exhibits diaphorase activity toward ferricyanide. |
