Showing papers by "B. de Kruijff published in 1987"
TL;DR: An in vitro transcription-translation and translocation system is developed to study the transport of PhoE protein and shows that the protein is synthesized as a larger precursor, which can be processed by purified leader peptidase and translocated into inverted inner membrane vesicles.
117 citations
TL;DR: The inhibition of respiratory chain activities in rat liver, rat heart and bovine heart mitochondria by the anthracycline antibiotic adriamycin was measured to support the conclusion that, in these three mitochondrial systems, the major drug-sensitive sites lie in complex III and IV.
97 citations
TL;DR: Results from the investigated fluorescence spectroscopy techniques suggest a deeper positioning of the tryptophan containing part of the peptide molecule in the cardiolipin system in comparison with the situation in phosphatidylcholine.
67 citations
TL;DR: It is proposed that the main driving force for H II phase formation is the tendency of gramicidin molecules to self-associate and organize into tubular structures such as found in the HII phase and that whether gramicIDin (analogs) form these or other types of aggregates depends on their tertiary structure, which is determined by intra- as well as intermolecular aromatic-aromatic stacking interactions.
66 citations
TL;DR: The interaction of melittin with bovine heart cardiolipin model membranes was investigated via bindingAssays, 31P-NMR, freeze-fracture electron microscopy, small angle X-ray diffraction and fluorescence based fusion assays, finding a strong binding appeared to be accompanied by the formation of large structures, resulting from a fusion process of extremely fast initial rate.
65 citations
TL;DR: Melittin is found to have an inverted phase inducing effect on these negatively charged lipids, in contrast to the influence on zwitterionic phospholipids.
64 citations
TL;DR: The hypothesis that gramicidin, by a combination of strong intermolecular attraction forces and its pronounced cone shape, has a strong tendency to organize, with the appropriate lipid, in intramembranous cylindrical structures such as is found in the HII phase is supported.
57 citations
TL;DR: The energetics of interaction and the type of aggregate structure in lateral assemblies of up to five gramicidin molecules in the beta 6.3 helical conformation at the air/water interface was calculated and further support the view that gramicIDin is a first example of a new class of hydrophobic polypeptides which can form cylindrical structures within the Hydrophobic core of the membrane.
51 citations
TL;DR: The channel conformation appears to be responsible for HII phase formation by gramicidin, and the solvent dependence depends on the solvent which is used to solubilize the peptide.
39 citations
TL;DR: In vivo 31P-NMR data demonstrate that adriamycin treatment is accompanied by a decrease of the cardiac phosphocreatine/ATP ratio which might be an expression of the well-established cardiotoxicity of the drug.
39 citations
TL;DR: Using 31P nuclear magnetic resonance (NMR), small-angle X-ray scattering (SAXS), and freeze-fracture electron microscopic (FFEM) techniques, it is shown that gramicidin induces a hexagonal HII phase not only in liposomes prepared from total lipids extracted from human erythrocytes but also in isolated human ERYthrocyte membranes (white ghosts).
Abstract: Using 31P nuclear magnetic resonance (NMR), small-angle X-ray scattering (SAXS), and freeze-fracture electron microscopic (FFEM) techniques, it is shown that gramicidin induces a hexagonal HII phase not only in liposomes prepared from total lipids extracted from human erythrocytes but also in isolated human erythrocyte membranes (white ghosts). A 37 degrees C, HII phase formation is detected at a gramicidin to phospholipid molar ratio exceeding 1:80. At a molar ratio of 1:5, about 30% of the phospholipid is organized in the HII phase. The gramicidin-induced HII phase exhibits a very small 31P chemical shift anisotropy [(CSA) approximately 10 +/- 1 ppm], indicating decreased head-group order, and it displays a temperature-dependent increase in tube diameter from 60.2 A at 4 degrees C to 64.2 A at 37 degrees C in ghosts and from 62.8 to 69.4 A at 37 degrees C in total lipid extracts, both in the presence of 1 mol of gramicidin/10 mol of phospholipid. This anomalous temperature-dependent behavior is probably due to the presence of cholesterol. 31P NMR data indicate that the HII phase formation by gramicidin is temperature dependent and show the gradual disappearance of the HII phase at low temperatures (less than 20 degrees C), resulting in a bilayer type of 31P NMR line shape at 4 degrees C, whereas SAXS and FFEM data suggest equal amounts of HII phases at all temperatures. This apparent discrepancy is probably the result of a decrease in the rate of lateral diffusion of the membrane phospholipids which leads to incomplete averaging of the 31P CSA in the HII phase.(ABSTRACT TRUNCATED AT 250 WORDS)
TL;DR: It is concluded that the charge interactions are required for binding and penetration of the protein and cholesterol can enhance the protein binding.
TL;DR: Experiments on the behaviour of monomolecular films at an air/water interface show that calcium-phosphatidate binding results in a decrease in the area of the polar region of the phosphatidate molecule, probably caused by headgroup dehydration and partial charge neutralization.
TL;DR: The hypothesis that the shape of gramicidin and its aggregational behaviour, in which the tryptophan residues play an essential role, are major determinants in the unique lipid structure modulating activity of gramICidin is supported.
TL;DR: Gramicidin A modulates the phase behaviour of lipid membranes and may play a role in the regulation of gene expression and these three distinct functions may all result from the arrangement of four tryptophan residues at the C-terminal end of the molecule.
01 Jan 1987
TL;DR: Whether such a complex lipid composition is a functional requirement and provokes the hypothesis that lipids contribute in more specific ways to membrane functions than by just forming a fluid impermeable matrix is provoked.
Abstract: Current concepts on the structure of biological membranes depict such a membrane as a liquid crystalline bilayer of lipid molecules in which penetrating protein structures are embedded. It is often assumed that the proteins are responsible for the specific properties of the membrane such as signal transduction and membrane transport, whereas the bilayer is there to provide a fluid matrix and to form an impermeable barrier. In view of such concepts the complexity of the lipid composition of a membrane is a striking fact. Although one suitable type of lipid could accomplish the requirements of a fluid matrix, most biological membranes appear to be built with complex mixtures of lipid species, showing many variations in size and charge of the polar headgroups, in length and unsaturation of the paraffin chains, and in cholesterol content [1]. For a given membrane the lipid composition is characteristic, but between membranes with different functions, large differences in composition can be noticed. This raises the question whether such a complex lipid composition is a functional requirement and provokes the hypothesis that lipids contribute in more specific ways to membrane functions than by just forming a fluid impermeable matrix.