Interaction between proteins and cationic gemini surfactant.
Surface tension, fluorescence, and circular dichroism (CD) methods have been used to investigate the interaction between cationic gemini surfactant 1,2-ethane bis(dimethyldodecylammonium bromide) (C12C2C12) and proteins including bovine serum albumin (BSA) and gelatin. Surface tension measurements show that the complexes of gelatin--C12C2C12 form more easily than that of BSA--C12C2C12. Addition of C12C2C12 has a different effect not only on the polarity of the microenvironment in BSA and gelatin systems but also on their fluorescence spectra. It can be seen from far-UV CD spectra that the alpha-helical network of BSA is disrupted and its content decreases from 41.7% to 27.6% while the random coil content of gelatin increases from 53.0% to 55.9% with increasing C12C2C12 concentration. The results from near-UV CD spectra show that the binding of C12C2C12 induces changes of the microenvironment around the aromatic amino acid residues and disulfide bonds of BSA at high C12C2C12 concentrations.
Wu
Dan
D
Key Laboratory of Colloid & Interface Chemistry, Shandong University, Education Ministry, Jinan 250100, PR China.
Xu
Guiying
G
Sun
Yuhai
Y
Zhang
Hongxing
H
Mao
Hongzhi
H
Feng
Yujun
Y
D000818:Animals; D002417:Cattle; D002942:Circular Dichroism; D005780:Gelatin / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D017433:Protein Structure, Secondary; D011506:Proteins / Q000737:chemistry*; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D012709:Serum Albumin / Q000737:chemistry / Q000378:metabolism; D013050:Spectrometry, Fluorescence; D013500:Surface Tension; D013501:Surface-Active Agents / Q000737:chemistry*
D011506:Proteins; D000644:Quaternary Ammonium Compounds; D012709:Serum Albumin; D013501:Surface-Active Agents; C046112:didodecyldimethylammonium; D005780:Gelatin