Persistent Link:
http://hdl.handle.net/10150/290546
Title:
The influence of substrate structure on organic cation transport
Author:
Bednarczyk, Dallas Joesph
Issue Date:
2001
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Using epifluorescence microscopy I have characterized the transport of the fluorescent organic cation NBD-TMA⁺, [2-(4-nitro-2,1,3-benzoxadiaxol-7-yl)aminoethyl]trimethylammonium. NBD-TMA⁺ has structural characteristics common to other secreted organic cations and it is fluorescent (λₑₓ = 458 nm; λ(em) = 530 nm). Transport of NBD-TMA⁺ by rabbit renal proximal tubules was time dependent, saturable, and inhibited by TEA⁺, cimetidine, and procainamide. These results provide strong evidence that the fluorescent organic cation, NBD-TMA⁺, is transported by the classical organic cation transporter and can be used to monitor organic cation transport in renal proximal tubules or cells expressing organic cation transporters. Additionally, a stable line of HeLa cells expressing hOCT1 was used to investigate the structural and chemical characteristics influencing substrate binding to the transporter. I found that the systematic rotation of a planar hydrophobic mass about a vertical axis aligned with the positively charged nitrogen reduced the binding affinity of substrate for hOCT1 suggesting that hOCT1 possesses a lateral steric limitation not seen in the apical organic cation transporter. Furthermore, the addition of supraplanar hydrophobic mass to a planar chemical structure was found to increase the binding affinity for a substrate substantially more that expected for the increased hydrophobicity suggesting that the binding site for hOCT1 is not simply planar in nature, but may be better described as a pocket.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Biology, Animal Physiology.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Physiological Sciences
Degree Grantor:
University of Arizona
Advisor:
Wright, Stephen H.

Full metadata record

DC FieldValue Language
dc.language.isoen_USen_US
dc.titleThe influence of substrate structure on organic cation transporten_US
dc.creatorBednarczyk, Dallas Joesphen_US
dc.contributor.authorBednarczyk, Dallas Joesphen_US
dc.date.issued2001en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractUsing epifluorescence microscopy I have characterized the transport of the fluorescent organic cation NBD-TMA⁺, [2-(4-nitro-2,1,3-benzoxadiaxol-7-yl)aminoethyl]trimethylammonium. NBD-TMA⁺ has structural characteristics common to other secreted organic cations and it is fluorescent (λₑₓ = 458 nm; λ(em) = 530 nm). Transport of NBD-TMA⁺ by rabbit renal proximal tubules was time dependent, saturable, and inhibited by TEA⁺, cimetidine, and procainamide. These results provide strong evidence that the fluorescent organic cation, NBD-TMA⁺, is transported by the classical organic cation transporter and can be used to monitor organic cation transport in renal proximal tubules or cells expressing organic cation transporters. Additionally, a stable line of HeLa cells expressing hOCT1 was used to investigate the structural and chemical characteristics influencing substrate binding to the transporter. I found that the systematic rotation of a planar hydrophobic mass about a vertical axis aligned with the positively charged nitrogen reduced the binding affinity of substrate for hOCT1 suggesting that hOCT1 possesses a lateral steric limitation not seen in the apical organic cation transporter. Furthermore, the addition of supraplanar hydrophobic mass to a planar chemical structure was found to increase the binding affinity for a substrate substantially more that expected for the increased hydrophobicity suggesting that the binding site for hOCT1 is not simply planar in nature, but may be better described as a pocket.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectBiology, Animal Physiology.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplinePhysiological Sciencesen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorWright, Stephen H.en_US
dc.identifier.proquest3023504en_US
dc.identifier.bibrecord.b41957623en_US
All Items in UA Campus Repository are protected by copyright, with all rights reserved, unless otherwise indicated.