Quenching of the intrinsic fluorescence of bovine serum albumin by chlorpromazine and hemin
Braz. j. med. biol. res
; 37(7): 963-968, July 2004. graf
Article
em En
| LILACS
| ID: lil-360927
Biblioteca responsável:
BR1.1
ABSTRACT
The binding of chlorpromazine (CPZ) and hemin to bovine serum albumin was studied by the fluorescence quenching technique. CPZ is a widely used anti-psychotic drug that interacts with blood components, influences bioavailability, and affects function of several biomolecules. Hemin is an important ferric residue of hemoglobin that binds within the hydrophobic region of albumin with high specificity. Quenching of the intrinsic fluorescence of bovine serum albumin (BSA) was observed by selectively exciting tryptophan residues at 290 nm. Emission spectra were recorded in the range from 300 to 450 nm for each quencher addition. Stern-Volmer graphs were plotted, and the quenching constant estimated for BSA solution titrated with hemin at 25ºC was 1.44 (± 0.05) x 10(5) M-1. Results showed that bovine albumin tryptophans are not equally accessible to CPZ, in agreement with the idea that polar or charged quenchers have more affinity for amino acid residues on the outer wall of the protein. Hemin added to albumin solution at a molar ratio of 11 quenched about 25 percent of their fluorescence. The quenching effect of CPZ on albumin-hemin solution was stronger than on pure BSA. This increase can be the result of combined conformational changes in the structure of albumin caused firstly by hemin and then by CPZ. Our results suggest that the primary binding site for hemin on bovine albumin may be located asymmetrically between the two tryptophans along the sequence formed by subdomains IB and IIA, closer to tryptophan residue 212.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
LILACS
Assunto principal:
Espectrometria de Fluorescência
/
Antipsicóticos
/
Soroalbumina Bovina
/
Clorpromazina
/
Hemina
Limite:
Animals
Idioma:
En
Revista:
Braz. j. med. biol. res
Assunto da revista:
BIOLOGIA
/
MEDICINA
Ano de publicação:
2004
Tipo de documento:
Article
País de afiliação:
Brasil
País de publicação:
Brasil