Interaction between the antimicrobial peptide leucrocin and model membrane systems
This research project examines leucrocin – specifically leucrocin I - a novel antimicrobial peptide found in the leukocytes of the Siamese crocodile (Crocodylus siamensis) and the American alligator (Alligator mississippiensis), selected for its unique and highly effective disease-fighting properties. Very few studies have been devoted to the interactions between leucrocin and model membranes. This project focuses on the interactions between leucrocin and selected model membranes using infrared, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic light scattering (DLS) and Fluorescence techniques. The results from IR show a strong interaction between leucrocin and model membranes occurs through a change in conformation (except for cholesterol) and the involvement of the carbonyl, phosphate, acyl chains and ammonium groups. The strongest interaction is found in the presence of the DPPC/DOPC/cholesterol (DDCH) complex. DSC data shows that the heat required to break LEU-DDCH is greater than that required to break DDCH. Leucrocin stabilizes the model membrane DDCH. LEU-CHOL is also stable. DLS revealed that leucrocin is a very powerful AMP able to disrupt a model membrane with a very low concentration. Fluorescene provides evidence that the tyrosine residue of leucrocin is one of the probable binding sites for DDCH. The combined investigation of the structure of leucrocin by infrared and its stability by TGA and DSC led to the conclusion that the aggregation of leucrocin in the presence of model membranes is the result of the structural change, rather than purely a change in electrostatic interactions. It was also found that the thermal stability of cardiolipin, DDCH and cholesterol is increased in the presence of leucrocin. The correlations observed in these studies between the nature of the model membranes on the structure of antimicrobial peptide and their biophysical interactions, illustrates the significance of such studies in predicting interactions of antimicrobial peptides with cells.
Molecular biology|Genetics|Cellular biology|Biochemistry|Alternative Medicine
Angela Kelly Stone,
"Interaction between the antimicrobial peptide leucrocin and model membrane systems"
ETD Collection for Tennessee State University.