Giant liposomes as model membranes for immunological studies: spontaneous insertion of purified K1-antigen (poly-alpha-2,8-NeuAc) of Escherichia coli.

6533b83afe1ef96bd12a71cf

RESEARCH PRODUCT

Giant liposomes as model membranes for immunological studies: spontaneous insertion of purified K1-antigen (poly-alpha-2,8-NeuAc) of Escherichia coli.

Gero Decher Dieter Bitter-suermann Joachim Venzmer Christoph Weisgerber Helmut Ringsdorf

subject

Biophysics Fluorescent Antibody Technique Neuraminidase Biology medicine.disease_cause Biochemistry Models Biological Residue (chemistry)chemistry.chemical_compound Membrane Lipids medicine Escherichia coli Microscopy Phase-Contrast Escherichia coli HEPES chemistry.chemical_classification Liposome Antigens Bacterial Antibodies Monoclonal Water Cell Biology Phosphatidic acid biology.organism_classification Enterobacteriaceae Enzyme Membrane chemistry Biochemistry Solubility Immunoglobulin G Antigens Surface Liposomes Dimyristoylphosphatidylcholine

description

A flow chamber has been constructed to use giant liposomes (diameter 5-50 microns) as model membranes for immunological studies and other experiments involving the interaction with water-soluble compounds. As an example of immunological importance, the insertion of purified K-antigen from Escherichia coli K1 has been studied. Despite its large hydrophilic part (poly-alpha-2,8-NeuAc), which is capped at its potential reducing end with phosphatidic acid acting as a lipid anchor group, this water-soluble material is readily incorporated into liposomal membranes of dimyristoylphosphatidylcholine (DMPC). The incorporation has been proven by immunofluorescence using a FITC-labeled monoclonal anti-K1-IgG. Without the lipid residue, however, no binding of poly-alpha-2,8-NeuAc to the liposomes has been observed. This could be shown by using colominic acid, an oligomeric form of alpha-2,8-NeuAc with free reducing ends instead of purified K1-antigen. The possibility for further manipulation of this model system has been shown by using a poly-alpha-2,8-NeuAc cleaving enzyme (endoneuraminidase). The function of the endoneuraminidase has been proven by showing no binding of the antibody after enzyme treatment of K1-bearing liposomes as well as by rapid loss of fluorescence of a previously bound FITC-antibody.

year	journal	country	edition	language
1990-04-30	Biochimica et biophysica acta

10.1016/0005-2736(90)90127-a https://pubmed.ncbi.nlm.nih.gov/2185843