Spectral and Magnetic Studies of Metallocarboxypeptidase A's

Citation

Rosenberg, Robert Charles (1974) Spectral and Magnetic Studies of Metallocarboxypeptidase A's. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/4peh-5f16. https://resolver.caltech.edu/CaltechTHESIS:07132021-182715013

Abstract

Spectral and magnetic studies on the cobalt(II), nickel(II), and copper(II) derivatives of the zinc containing metalloenzyme carboxypeptidase A (CPA) are reported and discussed.

The absorption spectrum and magnetic moment of Co(II)-CPA are shown to be consistent with a five coordinate metal structure by comparison to the spectra and magnetic moments of a large number of pseudo-tetrahedral and five coordinate cobalt(II) complexes. The usefulness of magnetic susceptibility data in assigning coordination number for high-spin cobalt(II) metalloenzyme systems is demonstrated.

The absorption spectrum and magnetic moment of Ni(II)-CPA are consistent only with an octahedral ground state geometry. The effect of substrate and inhibitor on the spectrum of Ni(II)-CPA was studied.

The absorption and EPR spectra of Cu(II)-CPA were also investigated. A significant pseudo-tetrahedral distortion from planar coordination geometry is indicated for this derivative. The interaction of Cu(II)-CPA and the inhibitor sodium B-phenylpropionate was also studied.

The results of these studies and especially those of Ni (II)-C PA do not agree with the predictions of the entatic state hypothesis.

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