Abstract
Nitrous oxide reductase, which catalyzes the reduction of N20to NB, was purified in a largely oxidized form from Pseudomonas aeruginosa strain P2 by a simple anaerobic procedure toYield an enzyme with a PeptidePurity of 95-98%- For the native (dimeric) enzyme, Mr 120,000 and for thedenatured subunit, w = 739000. The enzyme contained four CU atoms/ subunit, was purple in color, and exhibited a broad absorption band at 550 nm with an extinction ‘Oeffi-
cient Of about ll*ooo “’ x cm” referenced to the dimer. Molecular heterogeneity may also explain the decreased optical absorbance and CD amplitude that resulted from the activation process. The data overall reinforce thee view that the absorption spectrum of nitrous oxide reductaseis not a good predictor of absolute activity.