Sucrose dependence on the human serum albumin–dehydroepiandrosterone binding Thermodynamic and fractal approach

In this paper, the effect of sucrose concentration (x) on the dehydroepiandrosterone (DHEA)–human serum albumin (HSA) binding was investigated by a biochromatographic approach. A mathematical development based on fractal geometry is proposed to provide a more realistic picture of the DHEA–HSA binding. The fractal dimension D of the cavity surface and the thermodynamic data of the binding mechanism were calculated at different sucrose concentrations in the bulk solvent. Results showed that under a critical sucrose concentration value xc (domain I), the enhancement of the DHEA–HSA binding intensity was principally due to the increase of hydrophobic interaction between DHEA and HSA cavity. Above xc (domain II), the salting-out agent levelled the HSA cavity surface irregularity and, consequently, the DHEA affinity for the HSA decreased. Moreover, for the domain II, the HSA–DHEA binding and the thermodynamic data are discussed using fractal concept of surface fluctuations.