Magnetic Circular Dichroism Spectroscopy as a Probe of Geometric and Electronic Structure of Cobalt(II)-Substituted Proteins:  Ground-State Zero-Field Splitting as a Coordination Number Indicator

1997 ◽  
Vol 119 (18) ◽  
pp. 4182-4196 ◽  
Author(s):  
James A. Larrabee ◽  
Christopher M. Alessi ◽  
Esi T. Asiedu ◽  
Justin O. Cook ◽  
Keith R. Hoerning ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Circular Dichroism ◽  
Coordination Number ◽  
Ground State ◽  
Magnetic Circular Dichroism ◽  
Zero Field ◽  
Zero Field Splitting ◽  
Field Splitting ◽  
Magnetic Circular Dichroism Spectroscopy ◽  
Circular Dichroïsm

scholarly journals Magnetization curves of haemoproteins measured by low-temperature magnetic-circular-dichroism spectroscopy

1980 ◽  
Vol 191 (2) ◽  
pp. 411-420 ◽  
Author(s):  
A J Thomson ◽  
M K Johnson
Keyword(s):  
Circular Dichroism ◽  
Cytochrome C ◽  
High Spin ◽  
Ground State ◽  
Magnetic Circular Dichroism ◽  
Striking Difference ◽  
Zero Field ◽  
Magnetization Curves ◽  
Horse Heart Cytochrome ◽  
Circular Dichroïsm

The magnetic-circular-dichroism (m.c.d.) spectra of methymyoglobin cyanide and oxidized horse heart cytochrome c were measured in the region of the Soret band over a range of temperatures from 1.5 to 50 K and in fields from 0 to 5T. A similar study has been made with reduced bovine heart cytochrome c oxidase, which contains one high-spin ferrous haem, namely a3. M.c.d. magnetization curves characteristic of an isolated Kramer's ground state with spin S = 1/2. These curves contrast with the magnetization curve of the high-spin ferrous haem with spin S = 2. The electronic ground state of the latter compound contains zero-field components that are thermally accessible over the temperature range of the experiment. Hence the magnetization curves are a complex nested set. The magnetization curves of the S = 1/2 proteins were analysed and it is shown that it is possible to make estimates of the ground-state g-factors even in the presence of rhombic anisotropy, provided that some knowledge of the polarizations of the electronic transitions is available. The striking difference between the m.c.d. magnetization curves of a simple S = 1/2 paramagnet and magnetically complex ground state should prove extremely useful when m.c.d. spectroscopy is sued to probe the magentic properties of metal centres in proteins, and should have wide application beyond the field of haemoproteins.

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