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Article: Complexation of ytterbium to human transferrin and its uptake by K562 cells

TitleComplexation of ytterbium to human transferrin and its uptake by K562 cells
Authors
KeywordsK562 cells
Recognition
Transferrin
Ytterbium
Issue Date2002
PublisherBlackwell Publishing Ltd. The Journal's web site is located at http://www.blackwellpublishing.com/journals/EJB
Citation
European Journal Of Biochemistry, 2002, v. 269 n. 24, p. 6082-6090 How to Cite?
AbstractThere is an increasing interest in the use of lanthanides in medicine. However, the mechanism of their accumulation in cells is not well understood. Lanthanide cations are similar to ferric ions with regard to transferrin binding, suggesting transferrin-receptor mediated transport is possible; however, this has not yet been confirmed. In order to clarify this mechanism, we investigated the binding of Yb3+ to apotransferrin by UV-Vis spectroscopy and stopped-flow spectrophotometry, and found that Yb3+ binds to apotransferrin at the specific iron sites in the presence of bicarbonate. The apparent binding constants of these sites showed that the affinity of Yb3+ is lower than that of Fe3+ and binding of Yb3+ in the N-lobe is kinetically favored while the C-lobe is thermodynamically favored. The first Yb3+ bound to the C-lobe quantitatively with a Yb/apotransferrin molar ratio of < 1, whereas the binding to the other site is weaker and approaches completeness by a higher molar ratio only. As demonstrated by 1H NMR spectra, Yb3+ binding disturbed the conformation of apotransferrin in a manner similar to Fe3+. Flow cytometric studies on the uptake of fluorescein isothiocyanate labeled Yb3+-bound transferrin species by K562 cells showed that they bind to the cell receptors. Laser scanning confocal microscopic studies with fluorescein isothiocyanate labeled Yb3+-bound transferrin and propidium iodide labeled DNA and RNA in cells indicated that the Yb3+ entered the cells. The Yb3+-transferrin complex inhibited the uptake of the fluorescein labeled ferric-saturated transferrin (Fe2-transferrin) complex into K562 cells. The results demonstrate that the complex of Yb3+-transferrin complex was recognized by the transferrin receptor and that the transferrin-receptor-mediated mechanism is a possible pathway for Yb3+ accumulation in cells.
Persistent Identifierhttp://hdl.handle.net/10722/70072
ISSN
2006 Impact Factor: 3.579
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorDu, XLen_HK
dc.contributor.authorZhang, TLen_HK
dc.contributor.authorYuan, Len_HK
dc.contributor.authorZhao, YYen_HK
dc.contributor.authorLi, RCen_HK
dc.contributor.authorWang, Ken_HK
dc.contributor.authorYan, SCen_HK
dc.contributor.authorZhang, Len_HK
dc.contributor.authorSun, Hen_HK
dc.contributor.authorQian, ZMen_HK
dc.date.accessioned2010-09-06T06:19:27Z-
dc.date.available2010-09-06T06:19:27Z-
dc.date.issued2002en_HK
dc.identifier.citationEuropean Journal Of Biochemistry, 2002, v. 269 n. 24, p. 6082-6090en_HK
dc.identifier.issn0014-2956en_HK
dc.identifier.urihttp://hdl.handle.net/10722/70072-
dc.description.abstractThere is an increasing interest in the use of lanthanides in medicine. However, the mechanism of their accumulation in cells is not well understood. Lanthanide cations are similar to ferric ions with regard to transferrin binding, suggesting transferrin-receptor mediated transport is possible; however, this has not yet been confirmed. In order to clarify this mechanism, we investigated the binding of Yb3+ to apotransferrin by UV-Vis spectroscopy and stopped-flow spectrophotometry, and found that Yb3+ binds to apotransferrin at the specific iron sites in the presence of bicarbonate. The apparent binding constants of these sites showed that the affinity of Yb3+ is lower than that of Fe3+ and binding of Yb3+ in the N-lobe is kinetically favored while the C-lobe is thermodynamically favored. The first Yb3+ bound to the C-lobe quantitatively with a Yb/apotransferrin molar ratio of < 1, whereas the binding to the other site is weaker and approaches completeness by a higher molar ratio only. As demonstrated by 1H NMR spectra, Yb3+ binding disturbed the conformation of apotransferrin in a manner similar to Fe3+. Flow cytometric studies on the uptake of fluorescein isothiocyanate labeled Yb3+-bound transferrin species by K562 cells showed that they bind to the cell receptors. Laser scanning confocal microscopic studies with fluorescein isothiocyanate labeled Yb3+-bound transferrin and propidium iodide labeled DNA and RNA in cells indicated that the Yb3+ entered the cells. The Yb3+-transferrin complex inhibited the uptake of the fluorescein labeled ferric-saturated transferrin (Fe2-transferrin) complex into K562 cells. The results demonstrate that the complex of Yb3+-transferrin complex was recognized by the transferrin receptor and that the transferrin-receptor-mediated mechanism is a possible pathway for Yb3+ accumulation in cells.en_HK
dc.languageengen_HK
dc.publisherBlackwell Publishing Ltd. The Journal's web site is located at http://www.blackwellpublishing.com/journals/EJBen_HK
dc.relation.ispartofEuropean Journal of Biochemistryen_HK
dc.rightsEuropean Journal of Biochemistry. Copyright © Blackwell Publishing Ltd.en_HK
dc.subjectK562 cellsen_HK
dc.subjectRecognitionen_HK
dc.subjectTransferrinen_HK
dc.subjectYtterbiumen_HK
dc.titleComplexation of ytterbium to human transferrin and its uptake by K562 cellsen_HK
dc.typeArticleen_HK
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=0014-2956&volume=269&spage=6082&epage=6090&date=2002&atitle=Complexation+of+ytterbium+to+human+transferrin+and+its+uptake+by+K562+cellsen_HK
dc.identifier.emailSun, H:hsun@hkucc.hku.hken_HK
dc.identifier.authoritySun, H=rp00777en_HK
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1046/j.1432-1033.2002.03326.xen_HK
dc.identifier.pmid12473103en_HK
dc.identifier.scopuseid_2-s2.0-18744411774en_HK
dc.identifier.hkuros75921en_HK
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-18744411774&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume269en_HK
dc.identifier.issue24en_HK
dc.identifier.spage6082en_HK
dc.identifier.epage6090en_HK
dc.identifier.isiWOS:000179772800010-
dc.publisher.placeUnited Kingdomen_HK
dc.identifier.scopusauthoridDu, XL=15743529000en_HK
dc.identifier.scopusauthoridZhang, TL=7404374259en_HK
dc.identifier.scopusauthoridYuan, L=7402013480en_HK
dc.identifier.scopusauthoridZhao, YY=7406632284en_HK
dc.identifier.scopusauthoridLi, RC=36067806700en_HK
dc.identifier.scopusauthoridWang, K=7501398590en_HK
dc.identifier.scopusauthoridYan, SC=7401744858en_HK
dc.identifier.scopusauthoridZhang, L=8085225300en_HK
dc.identifier.scopusauthoridSun, H=7404827446en_HK
dc.identifier.scopusauthoridQian, ZM=7201384672en_HK

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