Interactions of beta-lactoglobulin with sodium decylsulfonate, decyltriethylammonium bromide, and their mixtures.
The interactions of beta-lactoglobulin (BLG) with anionic surfactant sodium decylsulfonate (C10SO3), cationic surfactant decyltriethylammonium bromide (C10NE), and the mixtures of cationic-anionic surfactants (C10NE-C10SO3) were investigated by circular dichroism (CD) and fluorescence methods. At pH 7.0, C10NE and the C10NE-rich surfactant mixtures of C10NE-C10SO3 could form precipitates with BLG, while C10SO3, equimolar mixtures of C10NE-C10SO3, or C10SO3-rich mixtures of C10NE-C10SO3 form homogeneous solutions with BLG. CD observed that both C10NE and C10SO3 could change the BLG structure. The effects of the mixtures of C10NE-C10SO3 on BLG structure depended on the ratio of C10NE to C10SO3. The C10NE-rich or the C10SO3-rich mixtures of C10NE-C10SO3 could significantly affect BLG structure, while the equimolar mixtures of C10NE-C10SO3 exhibited weaker interaction with BLG. Fluorescence measurements showed that both C10NE and C10SO3 could induce the enhancement of fluorescence of BLG, and C10NE enhanced the BLG fluorescence more than C10SO3 did. The effect of the mixtures of C10NE-C10SO3 on the fluorescence of BLG became stronger with the increase of the molar fraction of C10NE in C10NE-C10SO3 mixtures.
College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, PR China.
Run-Chao
RC
Lu
Ao-Neng
AN
Cao
Lu-Hua
LH
Lai
Jin-Xin
JX
Xiao
D001224:Aspartic Acid / Q000032:analysis; D001665:Binding Sites; D002412:Cations; D002942:Circular Dichroism; D018698:Glutamic Acid / Q000032:analysis; D007782:Lactoglobulins / Q000737:chemistry*; D008958:Models, Molecular; D011485:Protein Binding; D011487:Protein Conformation; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D013451:Sulfonic Acids / Q000737:chemistry*; D013501:Surface-Active Agents
D002412:Cations; D007782:Lactoglobulins; D000644:Quaternary Ammonium Compounds; D013451:Sulfonic Acids; D013501:Surface-Active Agents; C054210:N,N,N-triethyl-1-dodecylammonium; D001224:Aspartic Acid; D018698:Glutamic Acid; C517619:sodium decylsulfonate