INTERACTION OF CYSTEAMINE OXYGENASE WITH ORTHO-PHENANTHROLINE

The addition of o‐phenanthroline to a solution of cysteamine oxygenase produces only a slight increase of the absorbancy at 510 nm. The absorbancy is much higher when o‐phenanthroline is added in the presence of urea or in the presence of sodium dodecyl sulfate. The further addition of dithiothreitol exhibits a cooperative effect with the denaturant which has been explained with the cleavage of enzymic disulfide bonds. Absorbancies at 327 and 342 nm are also seen when o‐phenanthroline is added in the presence of sodium dodecyl sulfate. These are typical of the complex of o‐phenanthroline with Zn, in agreement with the analytical data indicating the occurrence of Zn in the enzyme. The need of denaturants for the reaction of the enzymic metals suggests that these metals are buried into the protein and should be regarded as an integral part of the enzyme structure. Copyright © 1969, Wiley Blackwell. All rights reserved