Faculty Collaboration Database

Binding and state of aggregation of spin-labeled cecropin AD in phospholipid bilayers: effects of surface charge and fatty acyl chain length. Biochemistry 1994 May 31;33(21):6691-9

Date

05/31/1994

Pubmed ID

8204604

DOI

10.1021/bi00187a040

Scopus ID

2-s2.0-0028243155 (requires institutional sign-in at Scopus site)   45 Citations

Abstract

The binding and state of aggregation of cecropin in large unilamellar vesicles of different surface potential and varying acyl chain length were examined using a Cys-33 spin-labeled derivative of cecropin AD (CAD). Association isotherms of the peptide were measured for vesicles of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC) containing 5, 15, and 30 mol % 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylglycerol (POPG). The isotherms display a concentration-dependent positive cooperativity indicating the possible formation of cecropin aggregates in the lipid phase. The critical aqueous concentration for aggregation was dependent on the fraction of POPG, suggesting the involvement of acidic lipids in the formation and stabilization of the putative aggregate. Our data also indicate that cooperativity depends on the state of side-chain ionization of an acidic residue that titrates between pH 7 and 4.4. The binding of spin-labeled Cys-33 CAD was found to be influenced by the acyl chain length of the host lipid. The association isotherm of the peptide for dilaureoyl-sn-glycero-3-phosphatidylcholine vesicles containing 30 mol % dilauroyl-sn-glycero-3-phosphatidylglycerol (DLPG) differed significantly from that in POPC/POPG and could be interpreted in terms of a monomer-monomer partitioning between the aqueous and lipid phases. ESR line-shape analysis was consistent with peptide aggregation in dioleoyl-sn-glycero-3-phosphatidylglycerol vesicles but not in DLPG vesicles.(ABSTRACT TRUNCATED AT 250 WORDS)

Author List

Mchaourab HS, Hyde JS, Feix JB

Author

Jimmy B. Feix PhD Emeritus Professor in the Biophysics department at Medical College of Wisconsin

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

Amino Acid Sequence
Anti-Infective Agents
Binding Sites
Electrochemistry
Electron Spin Resonance Spectroscopy
Fatty Acids
Hydrogen-Ion Concentration
Insect Hormones
Insect Proteins
Lipid Bilayers
Molecular Sequence Data
Phosphatidylcholines
Phosphatidylglycerols
Spin Labels
Temperature