Magnetic susceptibility studies of laccase and oxyhemocyanin
Abstract
The magnetic susceptibility of Rhus vernicifera laccase has been remeasured over the temperature range 5-260 K. In contrast to our previous results [Solomon, E. L, Dooley, D. M., Wang, R.-H., Gray, H. B., Cerdonio, M., Mogno, F. & Romani, G. L. (1975) J. Am. Chem. Soc. 98, 1029-1031] linear X versus T(-1) behavior was observed. The susceptibility of Limulus polyphemus oxyhemocyanin has also been measured in the range 5-260 K. Only weak paramagnetism, attributable to dissolved oxygen and a small amount of paramagnetic impurities, was observed. Analysis of the data establishes a lower limit of 550 cm(-1) for J, consistent with our earlier work. The temperature dependence of the susceptibility of laccase is quantitatively accounted for by the presence of two paramagnetic copper ions (types 1 and 2) per enzyme molecule. Curie law behavior at low temperatures rules out significant interaction between the two copper types, indicating that these redox centers are well separated (several angstroms) and are not connected by bridging ligands. Formulation of the type 3 site as binuclear Cu(II) requires J ≥ 500 cm(-1).
Additional Information
© 1978 by the National Academy of Sciences. Contributed by Harry B. Gray, April 17, 1978. We are greatly indebted to Ray Sarwinski and Mike Simmons of SHE Corporation for assistance with the experiments and for much helpful advice. We thank Grant Mauk for the preparation of Limulus hemocyanin. D.M.D. acknowledges a National Institutes of Health predoctoral traineeship (1974-1978) and R.A.S. acknowledges a National Science Foundation Graduate Fellowship (1975-1978). Research at the California Institute of Technology was supported by National Science Foundation Grant CHE77-11389. This is contribution 5765 from the Arthur Amos Noyes Laboratory. The costs of publication of this article were defrayed in part by the payment of page charges This article must therefore be hereby marked "advertisement" in accordance with 18 U. S. C. §1734 solely to indicate this fact.Attached Files
Published - DOOpnas78.pdf
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Additional details
- PMCID
- PMC392703
- Eprint ID
- 946
- Resolver ID
- CaltechAUTHORS:DOOpnas78.844
- NIH Predoctoral Fellowship
- NSF Graduate Research Fellowship
- NSF
- CHE77-11389
- Created
-
2005-11-15Created from EPrint's datestamp field
- Updated
-
2022-10-05Created from EPrint's last_modified field
- Other Numbering System Name
- Arthur Amos Noyes Laboratory of Chemical Physics
- Other Numbering System Identifier
- 5765