| A nuclear magnetic resonance study of the heme environment in beef liver catalase. | |
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MedLine Citation:
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PMID: 945745 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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The effect of high-spin heme iron in beef liver catalase on the longitudinal and transverse proton relaxation rates of the solvent has been used to probe the environment of the paramagnetic center. The longitudinal proton relaxation rates were measured as a function of temperature (5-31 degrees C), frequency (5-100 MHz), and pH. T1p was found to be pH independent in the range 6-11, indicating that no significant difference occurs in the heme surrounding within this pH range. The ligands formate and acetate, which preserve the spin state of the heme iron upon ligation, displace a water molecule from the sixth coordination position. This reaction is pH independent, while the binding measured by optical spectroscopy is pH dependent. The electron methanol and ethanol essentially do not change the proton relaxation rates. The temperature and frequency dependencies indicate that the relaxation times are governed by the electronic relaxation time of the high-spin ferric iron tau s. Tau s, which was found to be frequency independent, could not be determined from the T1p/T2p ratio, but only from the frequency dependence of the longitudinal relaxation rate at low frequencies. The results of the least-squares fit of the data to the theory indicate that there is one iron-bound rapidly exchanging water molecule. For the Fe3+ ion it was determined that tau s = 7 x 10(-11) s. |
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Authors:
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A Lanir; A Schejter |
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Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: Biochemistry Volume: 15 ISSN: 0006-2960 ISO Abbreviation: Biochemistry Publication Date: 1976 Jun |
Date Detail:
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Created Date: 1976-09-25 Completed Date: 1976-09-25 Revised Date: 2003-11-14 |
Medline Journal Info:
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Nlm Unique ID: 0370623 Medline TA: Biochemistry Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 2590-6 Citation Subset: IM |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Binding Sites Catalase* Cattle Heme / analysis Liver / enzymology* Magnetic Resonance Spectroscopy Mathematics Protein Binding Protein Conformation Temperature |
| Chemical | |
Reg. No./Substance:
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14875-96-8/Heme; EC 1.11.1.6/Catalase |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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