Document Detail

Adenine nucleotide translocase greatly increases the partition of trinitrophenyl-ATP into reduced Triton X-100 micelles.
MedLine Citation:
PMID:  1420926     Owner:  NLM     Status:  MEDLINE    
The presence of adenine nucleotide translocase (ANT) was found to greatly enhance the partitioning of the ATP analog 2',3'-O-(2,4,6-trinitrophenyl)-adenosine 5'-triphosphate (TNP-ATP) into reduced Triton X-100 micelles. The protein's effect was studied through the quenching of fluorescence of purified ANT, irreversibly inhibited by carboxyatractyloside (CAT), solubilized in reduced Triton X-100 micelles. The dependence of quenching of the protein's time-resolved tryptophan fluorescence on TNP-ATP concentration was measured and found to follow a Stern-Volmer mechanism. However, the calculated quenching constant was too large to be accounted for by the aqueous TNP-ATP concentration. Experiments were therefore conducted to determine the partitioning of the quencher between the three phases present: aqueous, protein-free micelle, and protein micelle; a system also described by the equation of Omann, G. M., and M. Glaser (1985. Biophys. J. 47:623-627.). By measuring the dependence of the apparent quenching rate constant on the protein concentration and protein/micelle ratios, this equation was used to calculate both the quencher partition coefficient into protein-free micelles (Pm) and into protein-micelles (Ppm), as well as the bimolecular quenching rate constant (kpm) in protein micelles. From the quenching experiments, kpm = 5.0 x 10(8)M-1s-1,Pm = 290 and pyrene quenching experiment to be 325, and by a rapid filtration experiment to be 450. Clearly, the presence of the integral membrane protein ANT-CAT in reduced Triton X-100 micelles greatly increases the partition of TNP-ATP into the micelle. ANT alters the properties and thus, the structure of the detergent micelle, which has direct implications for the use of detergent micelles as a model system for membrane proteins and may indicate that analogous effects occur in the mitochondrial membrane.
P J Tummino; A Gafni
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Biophysical journal     Volume:  63     ISSN:  0006-3495     ISO Abbreviation:  Biophys. J.     Publication Date:  1992 Oct 
Date Detail:
Created Date:  1992-12-11     Completed Date:  1992-12-11     Revised Date:  2010-09-07    
Medline Journal Info:
Nlm Unique ID:  0370626     Medline TA:  Biophys J     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1071-80     Citation Subset:  IM    
Institute of Gerontology, University of Michigan, Ann Arbor 48109.
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MeSH Terms
Adenosine Triphosphate / analogs & derivatives*,  chemistry
Atractyloside / analogs & derivatives
Chromatography, Gel
Energy Transfer
Mitochondria, Heart / enzymology
Mitochondrial ADP, ATP Translocases / isolation & purification,  metabolism*
Polyethylene Glycols*
Spectrometry, Fluorescence / methods
Grant Support
Reg. No./Substance:
0/Detergents; 0/Micelles; 0/Polyethylene Glycols; 17754-44-8/Atractyloside; 35988-42-2/carboxyatractyloside; 56-65-5/Adenosine Triphosphate; 61368-63-6/2',3'-O-(2,4,6-trinitro-cyclohexadienylidine)adenosine 5'-triphosphate; 9002-93-1/Octoxynol; 9068-80-8/Mitochondrial ADP, ATP Translocases

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