Sensitivity of P-glycoprotein tryptophan residues to benzodiazepines and ATP interaction

• Type: Article in International Scientific Journal
• Date: 2007

Authors

Sofia A.C. Lima (Author) Other; Anabela Cordeiro-da-Silva (Author) FFUP; de Castro, B (Author) FCUP; Paula Gameiro (Author) Other

Journal

Title: Biophysical Chemistry

Vol. 125 No. 1

Pages: 143-150

ISSN: 0301-4622

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 19 Citations

ISI Web of Science

Scopus - 18 Citations

Scientific classification

FOS: Medical and Health sciences > Other medical sciences

CORDIS: Health sciences

Other information

Authenticus ID: P-004-CMK

Resumo (PT): Plasma membrane P-glycoprotein is a member of the ATP-binding cassette family of membrane transporters. In the present study tryptophan intrinsic fluorescence was used to understand the P-glycoprotein response to three benzodiazepines (bromazepam, chlordiazepoxide and flurazepam) in the presence and absence of ATP. Fluorescence emission spectra showed a red shift on the maximal emission wavelength upon interaction of P-glycoprotein with all benzodiazepines. Benzodiazepine association with nucleotide-bound P-glycoprotein also showed this trend and the quenching profile was attributed to a sphere-of-action model, for static fluorescence. Furthermore, quenching data of benzodiazepinebound P-glycoprotein with ATP were concentration dependent and saturable, indicating that nucleotide binds to P-glycoprotein whether drug is present or not. These results seems in agreement with the proposal of the ATP-switch model by Higgins and Linton, where substrate binding to the transporters initiates the transport cycle by increasing the ATP binding affinity. <br> <br> Keywords: P-glycoprotein; Intrinsic fluorescence; Benzodiazepines; ATP; Interactions <br> <a target="_blank" href="http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TFB-4KG2K8T-1&_user=2460038&_coverDate=01%2F31%2F2007&_rdoc=15&_fmt=high&_orig=browse&_srch=doc-info(%23toc%235222%232007%23998749998%23637140%23FLA%23display%23Volume)&_cdi=5222&_sort=d&_docanchor=&_ct=26&_acct=C000057398&_version=1&_urlVersion=0&_userid=2460038&md5=04967cf9ad9cc124f419e1e23dbb4313"> Texto integral</a> <br> <br>

Abstract (EN): Plasma membrane P-glycoprotein is a member of the ATP-binding cassette family of membrane transporters. In the present study tryptophan intrinsic fluorescence was used to understand the P-glycoprotein response to three benzodiazepines (bromazepam, chlordiazepoxide and flurazepam) in the presence and absence of ATP. Fluorescence emission spectra showed a red shift on the maximal emission wavelength upon interaction of P-glycoprotein with all benzodiazepines. Benzodiazepine association with nucleotide-bound P-glycoprotein also showed this trend and the quenching profile was attributed to a sphere-of-action model, for static fluorescence. Furthermore, quenching data of benzodiazepinebound P-glycoprotein with ATP were concentration dependent and saturable, indicating that nucleotide binds to P-glycoprotein whether drug is present or not. These results seems in agreement with the proposal of the ATP-switch model by Higgins and Linton, where substrate binding to the transporters initiates the transport cycle by increasing the ATP binding affinity. <br> <br> Keywords: P-glycoprotein; Intrinsic fluorescence; Benzodiazepines; ATP; Interactions <br> <a target="_blank" href="http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TFB-4KG2K8T-1&_user=2460038&_coverDate=01%2F31%2F2007&_rdoc=15&_fmt=high&_orig=browse&_srch=doc-info(%23toc%235222%232007%23998749998%23637140%23FLA%23display%23Volume)&_cdi=5222&_sort=d&_docanchor=&_ct=26&_acct=C000057398&_version=1&_urlVersion=0&_userid=2460038&md5=04967cf9ad9cc124f419e1e23dbb4313"> Full text</a> <br> <br>

Language: Portuguese

Type (Professor's evaluation): Scientific