Faculty Collaboration Database

Response of phosphatidylcholine in the gel and liquid-crystalline states to membrane surface charges. Biochemistry 1991 Apr 09;30(14):3558-66

Date

04/09/1991

Pubmed ID

2012813

DOI

10.1021/bi00228a029

Scopus ID

2-s2.0-0025759056 (requires institutional sign-in at Scopus site)   70 Citations

Abstract

The influence of membrane surface charge on the conformation of the choline head group of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) was investigated in the gel and liquid-crystalline states by using 2H NMR spectroscopy of specifically choline-deuterated DMPC. The surface charge was made progressively more negative through admixture of various proportions of 1,2-dimyristoyl-sn-glycero-3-phosphoglycerol (DMPG). All membrane compositions showed nearly identical gel- to liquid-crystalline-phase transitions centered about 24 degrees C. The gel-state 2H NMR spectra from all three choline head-group deutero-labeling positions (alpha, beta, and gamma) decreased in intensity and broadened relative to the liquid-crystalline-state spectra. These effects were not so severe that they masked the overriding influence of surface charge on the choline head-group conformation as reflected in the 2H NMR spectra. Thus, in both the liquid-crystalline and gel states, the presence of negative surface charge caused the quadrupole splitting from DMPC-alpha-d2 to increase while causing that from DMPC-beta-d2 and DMPC-gamma-d9 to decrease. These effects were progressive with increasing density of negative surface charge. Correlation plots of the quadrupole splittings obtained, under otherwise identical conditions, from different deutero-labeling positions were linear over most of the range of surface charge densities, in both the liquid-crystalline and gel states, for all three correlations (alpha-beta, beta-gamma, and alpha-gamma). At extreme surface charge densities, the alpha-beta and alpha-gamma correlations showed biphasic behavior in that, at high surface charge densities, the change in the quadrupole splittings from DMPC-alpha-d2 became less pronounced.(ABSTRACT TRUNCATED AT 250 WORDS)

Author List

Macdonald PM, Leisen J, Marassi FM

Author

Francesca M. Marassi PhD Chair, Professor in the Biophysics department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Cell Membrane
Choline
Circular Dichroism
Deuterium
Dimyristoylphosphatidylcholine
Electrochemistry
Lipid Bilayers
Magnetic Resonance Spectroscopy
Phosphatidylcholines
Protein Conformation