Physicochemical Studies on the Interaction between N-Decanoyl-N-methylglucamide and Bovine Serum Albumin.
The protein-surfactant system constituted by bovine serum albumin (BSA) and N-decanoyl-N-methylglucamide (MEGA-10) has been studied by using surface tension, steady-state fluorescence, and dynamic light scattering measurements. It was found that the presence of protein delays the surfactant aggregation, which was interpreted as a sign of binding between surfactant and protein. Binding studies were carried out by two different methods. First, a treatment based on surface tension measurements was used to obtain information on the number of surfactant molecules bound per protein molecule under saturation conditions. Second, the binding curve for the BSA/MEGA-10 system was determined by examining the behavior of the intrinsic BSA fluorescence upon the surfactant addition. Both approaches indicate that the binding process is essentially cooperative in nature. The results of the aggregation numbers of MEGA-10 micelles, as well as those of resonance energy transfer from tryptophan residues to 8-anilinonaphthalene-1-sulfonate, corroborate the formation of micelle-like aggregates of surfactants, smaller than the free micelles, adsorbed on the protein surface. The dynamic light scattering results were not conclusive, in the sense that it was not possible to discriminate between protein-surfactant complexes and free micelles. However, the overall results suggest the formation of "pearl necklace" complexes in equilibrium with the free micelles of the surfactant.
Ruiz
C Carnero
CC
Grupo de Fluidos Estructurados y Sistemas Anfifílicos, Departamento de Física Aplicada II, Escuela Universitaria Politécnica, Universidad de Málaga, Campus de El Ejido, 29013 Málaga, Spain. ccarnero@uma.es
Hierrezuelo
J M
JM
Aguiar
J
J
Peula-García
J M
JM
D000817:Anilino Naphthalenesulfonates / Q000737:chemistry; D000818:Animals; D002417:Cattle; D004735:Energy Transfer; D005227:Fatty Acids / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000737:chemistry; D005944:Glucosamine / Q000031:analogs & derivatives* / Q000737:chemistry; D008027:Light; D012542:Scattering, Radiation; D012710:Serum Albumin, Bovine / Q000737:chemistry*; D013501:Surface-Active Agents / Q000737:chemistry*; D014364:Tryptophan / Q000737:chemistry
D000817:Anilino Naphthalenesulfonates; D005227:Fatty Acids; D005456:Fluorescent Dyes; D013501:Surface-Active Agents; D012710:Serum Albumin, Bovine; C027132:1-anilino-8-naphthalenesulfonate; C042221:decanoyl-N-methylglucamide; D014364:Tryptophan; D005944:Glucosamine