The epr spectra of the inhibitor derivatives of cobalt carbonic anhydrase

The epr spectra at 4.2 K of inhibitor derivatives of cobalt carbonic anhydrase have been recorded. The spectra can be grouped into two classes according to whether the low-field signal is broad or sharp and with g ranges of 6.1–6.8, 2.3–2.9, 1.6–1.8, and 5.8–6.2, 2.2–2.8, 1.5–1.8, respectively. The two kinds of spectra have been empirically related to the features of the room-temperature solution electronic spectra. A third kind of epr spectrum with a single broad signal is obtained when the inhibitor is in large excess. The possibility of using the epr spectra for deducing the geometry of cobalt enzymes is discussed.