US EPA

1489287 

Journal Article 

Fluorescence and circular dichroism studies on the interaction of bromocresol purple with bovine serum albumin 

Kamat, BP; Seetharamappa, J 

2004 

1 

Polish Journal of Chemistry
ISSN: 0137-5083 

78 

5 

723-732 

English 

WOS:000221388000012 

http://://WOS:000221388000012
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The mechanism of interaction of bromocresol purple (BCP)
with bovine serum albumin (BSA) has been investigated by spectrofluorometric and circular
dichroism. methods. Association constant for the BCP-BSA system showed that the interaction is
non-covalent in nature and that there occurs only a partial occupation of a binding site. Binding
studies in the presence of hydrophobic probe, 8-anilino-1-naphthalene sulphonic acid, sodium salt
(ANS) showed that there is hydrophobic interaction between BCP and ANS and they may share common
sites in BSA. Stern-Volmer analysis of fluorescence quenching data showed that the fraction of
fluorophore (protein) accessible to the quencher (BCP), was close to unity, indicating thereby
that both tryptophan residues of BSA are involved in dye-protein interaction. The rate constant
for quenching, greater than 10(10) M(-1)s(-1), indicated that the dye binding site is in close
proximity to tryptophan residue of BSA. Thermodynamic parameters, obtained from data at different
temperatures, showed that the binding of BCP to BSA involves hydrophobic bonds predominantly.
Fluorescence intensity data in the presence of additives showed that hydrophobic interaction
plays a prominent role. Significant decrease in concentration of free dye was observed for BCP in
presence of paracetamol. Circular dichroism studies revealed the change in helicity of BSA, due
to binding of BCP to BSA. 

bovine serum albumin; bromocresol purple; binding sites; interaction studies