Aa. Moosavimovahedi et al., MECHANISM OF DENATURATION OF BOVINE SERUM-ALBUMIN BY DODECYL TRIMETHYLAMMONIUM BROMIDE, International journal of biochemistry & cell biology, 28(9), 1996, pp. 991-998
Bovine serum albumin (BSA) denaturation has been extensively studied b
y different anionic and cationic surfactant. Dodecyl trimethylammonium
bromide (DTAB) is a cationic surfactant, and it is suggested that it
binds to the C-terminal section of BSA. In the present study, the ther
modynamical denaturation of BSA by dodecyl trimethylammonium bromide (
DTAB) has been studied with various experimental techniques. Equilibri
um dialysis, thermal denaturation, gel electrophoresis, titration micr
ocalorimetry at pH 7, I = 0.005, and different temperatures were all p
erformed. The enthalpy obtained from the van't Hoff relation and calor
imetry method as well as electrophoresis results were utilized to expl
ain the BSA tranistion state. Major findings included: the binding iso
therm shifts at a low free concentrations of DTAB and at a higher temp
erature suggest endothermicity for enthalpy of interaction; the calori
metry enthalpy (Delta H-cal) of interaction was smaller than the van't
Hoff enthalpy (Delta H-vH) for BSA-DTAB interaction; and the aggregat
ion of BS increased with increasing DTAB concentration. This study sug
gests that BSA unfolding induced by DTAB follows a multistate transiti
on model and does not follow the two-state mechanism assumed for most
single subunit proteins. Copyright (C) 1996 Elsevier Science Ltd