The interaction between the heme c and heme d moieties of Pseudomonas nitrite reductase as revealed by magnetic and natural circular dichroism studies. |
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Authors: | Y Orii H Shimada T Nozawa M Hatano |
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Affiliation: | 1. Department of Biology, Faculty of Science, Osaka University Toyonaka, Osaka 560, Japan;2. Chemical Research Institute of Non-aqueous Solutions, Tohoku University, Sendai 980, Japan |
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Abstract: | A possibility of a heme-heme interaction between the heme and heme moieties in nitrite reductase was examined by using magnetic and natural circular dichroism. The MCD of the heme moiety in the ferric enzyme was similar to that of mammalian ferricytochrome in shape and intensity, whereas in the reduced state the MCD intensity was considerably smaller than that of ferrocytochrome . When the heme moiety was perturbed by the complex formation with CO, imidazole or cyanide as well as by pH changes, the depressed MCD was restored to the MCD level of mammalian ferrocytochrome , accompanying conformational changes around the prosthetic groups. Thus, it was concluded that the heme-heme interaction exists only in the reduced enzyme and that this interaction is released under appropriate conditions. |
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