title: Intact human holo-transferrin interaction with oxaliplatin.
abstract: We report the interaction of intact human holo-transferrin (holo-Tf) with oxaliplatin (an anticancer drug), and the characterization of a complex composed of (1:1) intact holo-Tf and the parent oxaliplatin molecule using nanoelectrospray ionization quadrupole time-of-flight mass spectrometry (nanoESI-QTOF-MS). The molecular weight of this complex was determined to be 80,077 Da, which was an increase of 397 mass units compared to the protein alone (79,680 Da), suggesting that a parent drug molecule was bound to the intact protein. We further examined the interaction between the intact protein and oxaliplatin using size-exclusion high-performance liquid chromatography/inductively coupled plasma mass spectrometry (HPLC/ICPMS). The protein complex and free oxaliplatin were separated by HPLC and quantitatively determined by simultaneous monitoring of both 195Pt and 56Fe using ICPMS. The HPLC/ICPMS detected both Pt and Fe signals at retention time of 2.6 min, identifying the protein-drug complex. The Fe signal at 2.6 min did not change with the increase in incubation time of the reaction mixture containing holo-Tf and oxaliplatin, while the Pt signal at the same retention time increased over time, further demonstrating that the formation of this complex does not affect the protein-bound Fe. The binding constant of the (1:1) intact human holo-Tf-oxaliplatin complex was determined to be 7.7x10(5) M-1. Both nanoESI-MS and HPLC/ICPMS results support that the holo-Tf and parent oxaliplatin molecules form complexes through non-covalent binding, suggesting that holo-Tf may be a useful carrier for oxaliplatin delivery.
authors.affiliation: Environmental Health Sciences, Department of Public Health Sciences, Faculty of Medicine and Dentistry, University of Alberta, Canada T6G 2G3.
authors.forename: Yuan-Yuan
authors.initials: YY
authors.lastname: Zhao
authors.forename: Rupasri
authors.initials: R
authors.lastname: Mandal
authors.forename: Xing-Fang
authors.initials: XF
authors.lastname: Li
mesh_terms: D000970:Antineoplastic Agents / Q000032:analysis / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D004337:Drug Carriers / Q000032:analysis / Q000378:metabolism*; D006801:Humans; D009944:Organoplatinum Compounds / Q000032:analysis / Q000378:metabolism*; D000077150:Oxaliplatin; D011485:Protein Binding; D021241:Spectrometry, Mass, Electrospray Ionization; D014168:Transferrin / Q000032:analysis / Q000378:metabolism*
chemical_list: D000970:Antineoplastic Agents; D004337:Drug Carriers; D009944:Organoplatinum Compounds; D014168:Transferrin; D000077150:Oxaliplatin