Document Detail

Steric and electrostatic interactions govern nanofiltration of amino acids.
MedLine Citation:
PMID:  17335060     Owner:  NLM     Status:  MEDLINE    
Crossflow nanofiltration experiments were performed to investigate the factors influencing the removal of amino acids by a commercially available polymeric thin-film composite membrane. The removals of five monoprotic (Ala, Val, Leu, Gly, and Thr), one diprotic (Asp), and one dibasic (Arg) amino acids in a range of permeate fluxes, feed pH values, and ionic strengths were analyzed using a phenomenological model of membrane transport. At any given pH and ionic strength, reflection coefficients (rejection at asymptotically infinite flux) of monoprotic amino acids increased with molar radius demonstrating the role of steric interactions on their removal. Additionally, consistent with Donnan exclusion, higher reflection coefficients were obtained when the membrane and the amino acids both carried the same nature of charge (positive or negative). In other words, both co-ion repulsion and molecular size determined amino acids removal. Importantly, the removal of effectively neutral amino acids were significantly higher than neutral sugars and alcohols of similar size demonstrating that even near their isoelectric point, zwitterionic characteristics preclude them from being considered as strictly neutral.
Yongki Shim; Shankararaman Chellam
Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Biotechnology and bioengineering     Volume:  98     ISSN:  1097-0290     ISO Abbreviation:  Biotechnol. Bioeng.     Publication Date:  2007 Oct 
Date Detail:
Created Date:  2007-08-30     Completed Date:  2008-02-25     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  7502021     Medline TA:  Biotechnol Bioeng     Country:  United States    
Other Details:
Languages:  eng     Pagination:  451-61     Citation Subset:  IM    
Copyright Information:
(c) 2007 Wiley Periodicals, Inc.
Department of Civil and Environmental Engineering, University of Houston, Houston, Texas 77204-4003, USA.
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MeSH Terms
Amino Acids / isolation & purification*
Hydrogen-Ion Concentration
Nanotechnology / methods*
Osmolar Concentration
Static Electricity
Ultrafiltration / methods
Reg. No./Substance:
0/Amino Acids

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