| Stability and reactivation of tyrosine radicals from ribonucleotide reductase in tumor cells studied by ESR. | |
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MedLine Citation:
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PMID: 2536345 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Naturally occurring tyrosine radicals from the M2 subunit of ribonucleotide reductase (RR) have been recorded by ESR in proliferating ordinary Ehrlich-ascites (EA) tumor cells of mice. Tyrosine radicals are stable in EA cells at room temperature for 2 h. Up to 500 mW no microwave saturation occurs. The relatively high stability and non-saturation of tyrosine radicals in EA cells suggests a suitable protein conformation in the M2 subunit enabling a close contact between the tyrosine radical and the antiferromagnetic iron complex. This facilitates an ESR study of functionally essential tyrosine radicals of RR in EA cells at low temperature and recommends this cellular system for studying such processes as inhibition and activation, which change the content of tyrosine radicals of the proliferation-linked RR. Oxygen treatment of non-proliferating (quiescent) EA cells reactivates tyrosine radicals 2-3 fold as found in strongly proliferating cells. We conclude that in quiescent cells, suffering from a lack of oxygen due to their high density in the peritoneal cavity, a reactivation of tyrosine radicals occurs by oxidation of non-radical tyrosine residues of inactive M2 subunits. |
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Authors:
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G Lassmann; B Liermann; P Langen |
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Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: Free radical biology & medicine Volume: 6 ISSN: 0891-5849 ISO Abbreviation: Free Radic. Biol. Med. Publication Date: 1989 |
Date Detail:
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Created Date: 1989-03-09 Completed Date: 1989-03-09 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 8709159 Medline TA: Free Radic Biol Med Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 9-14 Citation Subset: IM |
Affiliation:
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Central Institute of Molecular Biology, Academy of Sciences of GDR, Berlin-Buch. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Animals Carcinoma, Ehrlich Tumor / enzymology* Cell Cycle Drug Stability Electron Spin Resonance Spectroscopy Free Radicals Mammary Neoplasms, Experimental / enzymology* Mice Microwaves Neoplasm Transplantation Oxygen / pharmacology Protein Conformation Ribonucleotide Reductases* Temperature Tyrosine* |
| Chemical | |
Reg. No./Substance:
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0/Free Radicals; 55520-40-6/Tyrosine; 7782-44-7/Oxygen; EC 1.17.4.-/Ribonucleotide Reductases |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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