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A fluorometric study of the interaction of bradykinin with lipids.

Appu Rao, A. G. and Setwart, J. M. and Vavrek, R. J. and Sillerud, L. O. and Fink, N. H. and Cann, J. R. (1989) A fluorometric study of the interaction of bradykinin with lipids. Biochimica et Biophysica Acta, 997. pp. 278-283.

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Abstract

The interaction of bradykinin (BK) with lipids has been followed by steady-state fluorescence measurements. Addition of either cerebroside sulfate (CS) or phosphatidylinositol (PI), solubilized with the nonionic surfactant C12E8, to BK or its analogue [Gly6].BK enhances the relative fluorescence intensity of peptide emission at 288 nm. Fiuorometric titration of the peptide with lipid has been used to quantitate the interactions in terms of stoichiometry and equilibrium constant. Job's method of continuous variation for the BK-CS interaction gave a stoichiometry of 1: 2 for the complex. The value of the equilibrium constant, K, for the interaction of either BK or [Gly61-BK with CS is 1.5.10 4 M-l. The BK-PI interaction is weaker; K-5.0- 103 M-I. Although electrostatic forces no doubt play a major role in these interactions, measurements on the model poptide Giy-Phe-Giy indicate that the phenylalanine residues of BK are disposed in the hydrophobic environment provided by the lipid-C12E8 mixed micelle. 13C-NMR measurements on [99% t3Ce-Gly6]-BK show that there is no change in its e/s/trans ratio upon interaction with CS. The increase in the relative fluorescence intensity of BK accompanying its cooperative interaction with sodium dodecyl sulfate (SDS) implicates the role of hydrophobic forces in this interaction as well. These results bear on the interpretation of the changes in circular dichroism (CD) of BK caused by SDS.

Item Type: Article
Uncontrolled Keywords: peptide hormone, bradykinin, lipids, steady-state fluorescence measurements
Subjects: 500 Natural Sciences and Mathematics > 04 Chemistry and Allied Sciences > 25 Peptide Chemistry
Divisions: Protein Chemistry and Technology
Depositing User: Food Sci. & Technol. Information Services
Date Deposited: 20 Mar 2018 04:22
Last Modified: 20 Mar 2018 04:22
URI: http://ir.cftri.res.in/id/eprint/2465

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