Document Detail


Active transport of amino acids by a guanidiniocarbonyl-pyrrole receptor.
MedLine Citation:
PMID:  20480464     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Herein we report the synthesis and characterization of a transporter 9 for N-acetylated amino acids. Transporter 9 is a conjugate of a guanidiniocarbonyl pyrrole cation, one of the most efficient carboxylate binding motifs reported so far, and a hydrophobic tris(dodecylbenzyl) group, which ensures solubility in organic solvents. In its protonated form, 9 binds N-acetylated amino acid carboxylates in wet organic solvents with association constants in the range of 10(4) M(-1) as estimated by extraction experiments. Aromatic amino acids are preferred due to additional cation-pi-interactions of the amino acid side chain with the guanidiniocarbonyl pyrrole moiety. U-tube experiments established efficient transport across a bulk liquid chloroform phase with fluxes approaching 10(-6) mol m(-2) s(-1). In experiments with single substrates, the release rate of the amino acid from the receptor-substrate complex at the interface with the receiving phase is rate determining. In contrast to this, in competition experiments with several substrates, the thermodynamic affinity to 9 becomes decisive. As 9 can only transport anions in its protonated form and has a pK(a) value of approximately 7, pH-driven active transport of amino acids is also possible. Transport occurs as a symport of the amino acid carboxylate and a proton.
Authors:
Christian Urban; Carsten Schmuck
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Chemistry (Weinheim an der Bergstrasse, Germany)     Volume:  16     ISSN:  1521-3765     ISO Abbreviation:  Chemistry     Publication Date:  2010 Aug 
Date Detail:
Created Date:  2010-08-30     Completed Date:  2010-11-26     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9513783     Medline TA:  Chemistry     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  9502-10     Citation Subset:  IM    
Affiliation:
Universität Duisburg-Essen, Institut für Organische Chemie, Universitätsstrasse 7, 45141 Essen, Germany.
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MeSH Terms
Descriptor/Qualifier:
Amino Acids / chemistry,  metabolism*
Anions / chemistry,  metabolism
Binding Sites
Biological Transport, Active / physiology*
Cations / chemistry,  metabolism*
Guanidine / chemistry,  metabolism*
Molecular Structure
Pyrroles / chemistry,  metabolism*
Solvents / chemistry
Chemical
Reg. No./Substance:
0/Amino Acids; 0/Anions; 0/Cations; 0/Pyrroles; 0/Solvents; 113-00-8/Guanidine

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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