US EPA

1492443 

Journal Article 

Mechanism of interaction of vincristine sulphate and rifampicin with bovine serum albumin: A spectroscopic study 

Kamat, BP; Seetharamappa, J 

2005 

1 

Proceedings of the Indian Academy of Sciences - Chemical sciences
ISSN: 0253-4134 

117 

6 

649-655 

English 

10.1007/bf02708294 

WOS:000233975200005 

http://://WOS:000233975200005
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The mechanism of interaction of vincristine sulphate (VS)
and rifampicin (RF) with bovine serum albumin (BSA) has been studied by quenching of BSA
fluorescence by RF/VS. The Stern-Volmer plot indicates the presence of a static component in the
quenching mechanism. Results also show that both the tryptophan residues of BSA are accessible to
VS and RE The high magnitude of rate constant of quenching indicates that the process of energy
transfer occurs by intermolecular interaction and VS/RFbinding site is in close proximity to the
tryptophan residues of BSA. Binding studies in the presence of a hydrophobic probe, 8-anilino-1-
naphthalene-sulphonic acid sodium salt (ANS) indicate that the VS and RF compete with ANS for
hydrophobic sites on the surface of BSA. Small decreases in critical micellar concentrations
(CMC) of anionic surfactants in presence of VS/RF show that the ionic character of VS/RF also
contributes to binding. The temperature dependence of the association constant is used to
estimate the values of the thermodynamic parameters involved in the interaction of VS/RF with BSA
and the results indicate that hydrophobic forces play a significant role in the binding. Circular
dichroism studies reveal that the change in helicity of BSA are due to binding of VS/RF to BSA. 

vincristine sulphate; rifampicin; fluorescence quenching mechanism