Document Detail

Locating the Binding Sites of Folic Acid with Milk α- and β-Caseins.
MedLine Citation:
PMID:  22103859     Owner:  NLM     Status:  Publisher    
We located the binding sites of folic acid with milk α- and β-caseins at physiological conditions, using constant protein concentration and various folic acid contents. FTIR, UV-visible and fluorescence spectroscopic methods as well as molecular modeling were used to analyse folic acid binding sites, the binding constant and the effect of folic acid interaction on the stability and conformation of caseins. Structural analysis showed that folic acid binds caseins via both hydrophilic and hydrophobic contacts with overall binding constants of Kfolic -α--caseins = 4.8 (± 0.6) x 104 M-1 and Kfolic acid-β-caseins = 7.0 (± 0.9) x 104 M-1. The number of bound acid molecules per protein was 1.5 (±0.4) for α-casein and 1.4 (±0.3) for β-casein complexes. Molecular modeling showed different binding sites for folic acid on α- and β-caseins. The participation of several amino acids in folic acid-protein complexes was observed, which stabilized by hydrogen bonding network and the free binding energy of -7.7 kcal/mol (acid-α-casein) and -8.1 kcal/mol (acid-β-casein). Folic acid complexation altered protein secondary structure by reduction of α-helix from 35% (free α-casein) to 33% (acid-complex) and 32% ( free β-casein) to 26% (acid-complex) indicating a partial protein destabilization. Caseins might act as carriers for transportation of folic acid to target molecules.
Philippe- Bourassa; Heidar-Ali Tajmir-Riahi
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-11-21
Journal Detail:
Title:  The journal of physical chemistry. B     Volume:  -     ISSN:  1520-5207     ISO Abbreviation:  -     Publication Date:  2011 Nov 
Date Detail:
Created Date:  2011-11-22     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101157530     Medline TA:  J Phys Chem B     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
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