Abstract
From the bovine heart microsomes, a CO-binding hemoprotein has been solubilized with the aid of trypsin and extensively purified by fractionation with ammonium sulfate, chromatography on Sephadex, and electrophoresis on starch. The purified sample that migrates as a single band in electrophoresis at pH 9.5 and 12 possesses an extremely low peroxidase activity and contains a small amount of phosphorus. The pigment, when reduced, absorbs light at 423, 530, and 559 mμ at pH 9.5. The reduced pigment which combines with carbon monoxide is rapidly autoxidizable. Based on the α-absorption band of the ferrous spectrum at pH 9.5, the pigment was named hemoprotein 559. At pH 12, the α-band shifts to 557 mμ with a concomitant increase in absorbancy. The pH-dependent hyperchromism has been studied and interpreted as arising from the increased electronic transition probability in the porphyrin π-system.
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