English
 
Help Privacy Policy Disclaimer
  Advanced SearchBrowse

Item

ITEM ACTIONSEXPORT
  Binding of Phlorizin to the Isolated C-Terminal Extramembranous Loop of the Na+/Glucose Cotransporter Assessed by Intrinsic Tryptophan Fluorescence

Xia, X., Lin, J.-T., & Kinne, R. K. H. (2003). Binding of Phlorizin to the Isolated C-Terminal Extramembranous Loop of the Na+/Glucose Cotransporter Assessed by Intrinsic Tryptophan Fluorescence. Biochemistry, 42(20): 1, pp. 6115-6120. Retrieved from http://dx.doi.org/10.1021/bi020695b.

Item is

Files

show Files

Locators

show

Creators

show
hide
 Creators:
Xia, Xiaobing1, Author
Lin, Jiann-Tso2, Author              
Kinne, Rolf K. H.2, Author              
Affiliations:
1Max Planck Institute of Molecular Physiology, Max Planck Society, ou_1753286              
2Sonstige Wissenschaftliche Organisationseinheiten, Max Planck Institute of Molecular Physiology, Max Planck Society, ou_1753294              

Content

show
hide
Free keywords: -
 Abstract: Phlorizin, a phloretin 2'-glucoside, is a potent inhibitor of the Na+/glucose cotransporter (SGLT1). On the basis of transport studies in intact cells, a binding site for phlorizin was suggested in the region between amino acids 604-610 of the C-terminal loop 13. To further investigate phlorizin binding titration experiments of the intrinsic Trp fluorescence of isolated wild-type loop 13 and two mutated loops (Y604K and G609K) were carried out. Phlorizin (135 M) produced approximately 40% quenching of the fluorescence of wild-type loop 13; quenching could also be observed with the two mutated loops. The apparent Kd was lowest for the wild-type loop 13 (Kd 23 M), followed by mutant G609K (57 M) and mutant Y604K (70 M). Binding of phlorizin was further confirmed by a decrease of the accessibility of loop 13 to the collisional quencher acrylamide. The interaction involves the aromatic moiety of the aglucone since phloretin (the aglucone of phlorizin) showed almost the same effects as phlorizin, while D-glucose did not. MALDI-TOF experiments revealed that loop 13 contained a disulfide bond between Cys 560 and Cys 608 that is very important for phlorizin-dependent fluorescence quenching. These studies provide direct evidence that loop 13 is a site (important amino acids including 604-609) for the molecular interaction between SGLT1 and phlorizin. They confirm that the aglucone part of the glucoside is responsible for this interaction.

Details

show
hide
Language(s): eng - English
 Dates: 2003-04-26
 Publication Status: Published in print
 Pages: -
 Publishing info: -
 Table of Contents: -
 Rev. Type: Peer
 Identifiers: eDoc: 21589
URI: http://dx.doi.org/10.1021/bi020695b
 Degree: -

Event

show

Legal Case

show

Project information

show

Source 1

show
hide
Title: Biochemistry
Source Genre: Journal
 Creator(s):
Affiliations:
Publ. Info: -
Pages: - Volume / Issue: 42 (20) Sequence Number: 1 Start / End Page: 6115 - 6120 Identifier: -