| Determination by photoreduction of flip-flop kinetics of spin-labeled stearic acids across phospholipid bilayers. | |
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MedLine Citation:
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PMID: 9889351 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Spin-labeled stearic acid derivatives (N-DS) can be used to determine the rate at which lipid-derived drugs can cross a phospholipid bilayer (flip-flop). The flip-flop rate of N-DS (where N=5, 6, 7, 9, 10, 12, 16), was measured using vectorial photoreduction of nitroxides to their corresponding hydroxylamine by FMN, a charged, membrane-impermeable flavin, by hydrogen atom transfer from EDTA. From the time difference in the photoreduction rates of N-DS located in the outer and inner half of the bilayer, the flip-flop rate of N-DS across the bilayer can be determined. The results show that at pH 8.0 or lower, the photoreduction of 5-DS on one side of the membrane by FMN is slower than the flip-flop rate of 5-DS across phospholipid bilayers. For 5-DS at pH 7.0, this rate is at least 33.8+/-4.24 s or faster. Stearic acids with the spin label at different positions along the acyl chain (N=5, 6, 7, 9, 10, 12) have similar flip-flop rates in the liposomes at pH 7.0 although 16-DS is slower, probably due to the inaccessibility of the nitroxide moiety to FMN. It is most likely that the fast distribution of 5-DS in cells is due to the fast movement of acidic form, but not the salt form, of 5-DS across membrane bilayers. The oxazolidine (nitroxide moiety) does not seem to affect the pKa ( approximately 8.3) of stearic acid at air-water interface. Thus, N-DS are good probes for studying the distribution kinetics of stearic acid derivatives in biological systems. |
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Authors:
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J M Yuann; R D Morse |
Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S. |
Journal Detail:
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Title: Biochimica et biophysica acta Volume: 1416 ISSN: 0006-3002 ISO Abbreviation: Biochim. Biophys. Acta Publication Date: 1999 Jan |
Date Detail:
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Created Date: 1999-02-23 Completed Date: 1999-02-23 Revised Date: 2007-11-14 |
Medline Journal Info:
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Nlm Unique ID: 0217513 Medline TA: Biochim Biophys Acta Country: NETHERLANDS |
Other Details:
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Languages: eng Pagination: 135-44 Citation Subset: IM |
Affiliation:
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Department of Chemistry, Illinois State University, Normal, IL 61790-4160, USA. jyuann@chem.bu.edu |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Cyclic N-Oxides Electron Spin Resonance Spectroscopy Flavin Mononucleotide / chemistry Lipid Bilayers / chemistry* Membrane Fluidity Oxidation-Reduction Permeability Phospholipids / chemistry* Spin Labels Stearic Acids / chemistry* Temperature |
| Grant Support | |
ID/Acronym/Agency:
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GM 1415-44365-01/GM/NIGMS NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/Cyclic N-Oxides; 0/Lipid Bilayers; 0/Phospholipids; 0/Spin Labels; 0/Stearic Acids; 146-17-8/Flavin Mononucleotide |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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