Document Detail

Stopped-flow kinetic analysis of long-chain fatty acid dissociation from bovine serum albumin.
MedLine Citation:
PMID:  11964183     Owner:  NLM     Status:  MEDLINE    
The kinetics of the interaction of long-chain fatty acids (referred to as fatty acids) with albumin is critical to understanding the role of albumin in fatty acid transport. In this study we have determined the kinetics of fatty acid dissociation from BSA and the BSA-related fatty acid probe BSA-HCA (BSA labelled with 7-hydroxycoumarin-4-acetic acid) by stopped-flow methods. Fatty acid-albumin complexes of a range of natural fatty acid types and albumin molecules (donors) were mixed with three fatty acid-binding acceptor proteins. Dissociation of fatty acids from the donor was monitored by either the time course of donor fluorescence/absorbance or the time course of acceptor fluorescence. The results of these measurements indicate that fatty acid dissociation from BSA as well as BSA-HCA is well described by a single exponential function over the entire range of fatty acid/albumin molar ratios used in these measurements, from 0.5:1 to 6:1. The observed rate constants (k(obs)) for the dissociation of each fatty acid type reveal little or no dependence on the initial fatty acid/albumin ratio. However, dissociation rates were dependent upon the type of fatty acid. In the case of native BSA with an initial fatty acid/BSA molar ratio of 3:1, the order of k(obs) values was stearic acid (1.5 s(-1)) < oleic acid < palmitic acid congruent with linoleic acid<arachidonic acid (8 s(-1)) at 37 degrees C. The corresponding values for BSA-HCA were about half the values for BSA. The results of this study show that the rate of fatty acid dissociation from native BSA is more than 10-fold faster than reported previously and that the off-rate constants for the five primary fatty acid-binding sites differ by less than a factor of 2. We conclude that for reported rates of fatty acid transport across cell membranes, dissociation of fatty acids from the fatty acid-BSA complexes used in the transport studies should not be rate-limiting.
Erland J F Demant; Gary V Richieri; Alan M Kleinfeld
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The Biochemical journal     Volume:  363     ISSN:  0264-6021     ISO Abbreviation:  Biochem. J.     Publication Date:  2002 May 
Date Detail:
Created Date:  2002-04-19     Completed Date:  2002-06-10     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  2984726R     Medline TA:  Biochem J     Country:  England    
Other Details:
Languages:  eng     Pagination:  809-15     Citation Subset:  IM    
Department of Medical Biochemistry and Genetics, Biochemistry Laboratory C, The Panum Institute, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark.
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MeSH Terms
Carrier Proteins / metabolism
Fatty Acid-Binding Proteins
Fatty Acids / metabolism*
Fluorescent Dyes / metabolism
Indicators and Reagents
Neoplasm Proteins*
Recombinant Proteins*
Serum Albumin, Bovine / metabolism*
Spectrometry, Fluorescence
Grant Support
Reg. No./Substance:
0/Acetates; 0/Carrier Proteins; 0/Coumarins; 0/Fatty Acid-Binding Proteins; 0/Fatty Acids; 0/Fluorescent Dyes; 0/Indicators and Reagents; 0/Neoplasm Proteins; 0/Recombinant Proteins; 0/Serum Albumin, Bovine; 0/acrylodated intestinal fatty acid binding protein, recombinant; 6950-82-9/7-hydroxycoumarin-4-acetic acid

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