Linked Life Data

18630875

Source:http://linkedlifedata.com/resource/pubmed/id/18630875

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
5
pubmed:dateCreated
2008-10-7
pubmed:abstractText
This study examines the various equilibrium in situ secondary structures of the pharmaceutical heteropolypeptide, KL 4, in the solid state, in solution, and in the monolayer state alone and mixed with dipalmitoylphosphatidylcholine (DPPC) and palmitoyloleoylphosphatidylglycerol (POPG). In situ surface circular dichroism spectroscopy, using a method first reported by Damodaran (Damodaran, S. Anal. Bioanal. Chem. 2003, 376, 182-188), of equilibrated KL 4, DPPC/KL 4, POPG/KL 4, and DPPC/POPG/KL 4 monolayers at the air-water interface was used to examine the in situ two-dimensional conformation of KL 4. Gravimetric vapor sorption by solid KL 4 was used to analyze the effects of water molecules on the conformation of KL 4 when confined as a monolayer at the surface of water. Solid-state KL 4 conformation was determined by X-ray powder diffraction (XRPD). The equilibrium interfacial and spreading properties were measured at 25 degrees C, 37 degrees C, and 45 degrees C using the Wilhelmy plate method and Langmuir film balance. Equilibrium phase transition temperatures were measured using differential scanning calorimetry (DSC). It was found that solid-state KL 4, which takes up very little water, exhibits beta-sheet and alpha-helix secondary structures, whereas KL 4 in solution appears to exist only as an alpha-helix. KL 4 forms a stable, insoluble monolayer, exhibiting beta-sheet and aperiodic structures. These structures provide KL 4, when confined in two-dimensions, the structural flexibility to maximize favorable cationic lysine-water interactions and favorable leucine-leucine hydrophobic and van der Waals interactions; while effectively "shielding" the leucine residues away from water. In DPPC/KL 4 monolayers, KL 4 retains its native beta-sheet and aperiodic structures, consistent with phase separation of DPPC and KL 4 in bilayers and monolayers. In POPG/KL 4 monolayers, KL 4 exhibits an increase in aperiodic secondary structures (loss of beta-sheet) to maximize favorable electrostatic interactions, consistent with the observed negative deviations from ideal monolayer mixing.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:issn
1543-8384
pubmed:author
pubmed:issnType
Print
pubmed:volume
5
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
681-95
pubmed:meshHeading
pubmed-meshheading:18630875-1,2-Dipalmitoylphosphatidylcholine, pubmed-meshheading:18630875-Adsorption, pubmed-meshheading:18630875-Air, pubmed-meshheading:18630875-Calorimetry, Differential Scanning, pubmed-meshheading:18630875-Circular Dichroism, pubmed-meshheading:18630875-Drug Administration Routes, pubmed-meshheading:18630875-Lipid Bilayers, pubmed-meshheading:18630875-Models, Biological, pubmed-meshheading:18630875-Peptides, pubmed-meshheading:18630875-Phase Transition, pubmed-meshheading:18630875-Phosphatidylglycerols, pubmed-meshheading:18630875-Powder Diffraction, pubmed-meshheading:18630875-Protein Conformation, pubmed-meshheading:18630875-Protein Structure, Secondary, pubmed-meshheading:18630875-Pulmonary Surfactants, pubmed-meshheading:18630875-Surface Properties, pubmed-meshheading:18630875-Temperature, pubmed-meshheading:18630875-Water
pubmed:articleTitle
Characterization of the in situ structural and interfacial properties of the cationic hydrophobic heteropolypeptide, KL4, in lung surfactant bilayer and monolayer models at the air-water interface: implications for pulmonary surfactant delivery.
pubmed:affiliation
Division of Pharmaceutical Sciences, School of Pharmacy, University of Wisconsin-Madison, Madison, Wisconsin 53705, USA. hmmansour@unc.edu
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't