NMR studies on interaction of lauryl maltoside with cytochrome c oxidase: a model for surfactant interaction with the membrane protein.
Interaction of lauryl maltoside (LM) surfactant with bovine heart cytochrome c oxidase (CcO) has been studied by NMR techniques. Detailed 2-D (1)H and (13)C NMR techniques were used to assign the NMR signals of the surfactant nuclei. Paramagnetic dipolar shift of the surfactant (13)C NMR signals were used to identify the atoms close to the enzyme. The diamagnetic carbon monoxide complex of CcO did not cause any shift in the surfactant NMR spectra suggesting that the paramagnetic centres of the native CcO cause the shifts by dipolar interactions. The results showed that the polar head groups of the surfactant comprised of two maltoside rings are more affected, while the hydrophobic tail groups did not show any significant change on binding of the surfactant to the enzyme. This indicated that surfactant head groups possibly bind to the enzyme surface and the hydrophobic tail of the surfactant forms micelles and remains away from the enzyme. Based on the results, we propose that the membrane bound enzyme is possibly stabilised in aqueous solution by association with the micelles of the neutral surfactant so that the polar heads of the micelles bind to the polar surface of the enzyme. These micelles might form a 'belt like' structure around the enzyme helping it to remain monodispersed in the active form.
Chattopadhyay
Krishnananda
K
Department of Chemical Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumnai 400 005, India. krish@biochem.wustl.edu
Das
Tapan Kanti
TK
Majumdar
Ananya
A
Mazumdar
Shyamalava
S
D000818:Animals; D002417:Cattle; D003902:Detergents / Q000737:chemistry*; D003576:Electron Transport Complex IV / Q000737:chemistry* / Q000378:metabolism; D005960:Glucosides / Q000737:chemistry*; D008956:Models, Chemical; D015394:Molecular Structure; D009206:Myocardium / Q000201:enzymology*; D019906:Nuclear Magnetic Resonance, Biomolecular
D003902:Detergents; D005960:Glucosides; C040358:dodecyl maltoside; D003576:Electron Transport Complex IV