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Membrane Affinity (membrane + affinity)

Distribution by Scientific Domains

Chemistry	60%

Selected Abstracts

Mouse recombinant protein C variants with enhanced membrane affinity and hyper-anticoagulant activity in mouse plasma

FEBS JOURNAL, Issue 22 2009
Michael J. Krisinger
Mouse anticoagulant protein C (461 residues) shares 69% sequence identity with its human ortholog. Interspecies experiments suggest that there is an incompatibility between mouse and human protein C, such that human protein C does not function efficiently in mouse plasma, nor does mouse protein C function efficiently in human plasma. Previously, we described a series of human activated protein C (APC) Gla domain mutants (e.g. QGNSEDY-APC), with enhanced membrane affinity that also served as superior anticoagulants. To characterize these Gla mutants further in mouse models of diseases, the analogous mutations were now made in mouse protein C. In total, seven mutants (mutated at one or more of positions P10S12D23Q32N33) and wild-type protein C were expressed and purified to homogeneity. In a surface plasmon resonance-based membrane-binding assay, several high affinity protein C mutants were identified. In Ca2+ titration experiments, the high affinity variants had a significantly reduced (four-fold) Ca2+ requirement for half-maximum binding. In a tissue factor-initiated thrombin generation assay using mouse plasma, all mouse APC variants, including wild-type, could completely inhibit thrombin generation; however, one of the variants denoted mutant III (P10Q/S12N/D23S/Q32E/N33D) was found to be a 30- to 50-fold better anticoagulant compared to the wild-type protein. This mouse APC variant will be attractive to use in mouse models aiming to elucidate the in vivo effects of APC variants with enhanced anticoagulant activity. [source]

NMR spectroscopic characterization of the membrane affinity of polyols

MAGNETIC RESONANCE IN CHEMISTRY, Issue 11 2005
Daniela Fischer
Abstract Residual dipolar couplings (RDCs) are applied here for the analysis of weak, transient binding events between phosphatidylcholine bilayers and polyols. Large signal responses are observed even for low percentages of ,ligand-receptor complexes,' making RDCs a sensitive tool for the analysis of molecular recognition events. The different degree of alignment in solution can be compared as a result of the calculation of the alignment tensor elements. By varying polarity and/or charge of the molecules under investigation, nonspecific hydrophobic effects can be excluded. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Interactive functional poly(vinylidene fluoride) membranes with modulated lysozyme affinity: a promising class of new interfaces for contactor crystallizers

POLYMER INTERNATIONAL, Issue 12 2009
Annarosa Gugliuzza
Abstract BACKGROUND: One of the challenges of current researches in biotechnological fields is the achievement of regular and increasingly smaller protein crystals for genomics and biocatalyst applications. The membrane contactor-based methodology appears to be a time-effective and economically competitive technology for accomplishing this target. RESULTS: A new class of interactive polymeric interfaces enabling the nucleation of very small protein crystals in a short time through controlling attractive interactions is discussed. Specifically, the role of attractive interfacial forces between a model lysozyme solution and modified poly(vinylidene fluoride) membranes is examined. The insertion of amphiphilic motifs in the fluorinated membranes allows quicker agglomeration of protein crystals at the membrane surface reducing significantly the induction time for protein nucleation. The chemical nature of the modifier permits the modulation of the membrane affinity to the lysozyme, involving polar and non-polar attractive interactions and preserving intrinsic structural features, transport properties and the hydrophobic character of the interfaces, according to the basics of membrane crystallization technology. The formation of critical nuclei is observed after 3 h and micro-sized crystals are formed in less than 24 h. CONCLUSION: The experimental evidence suggests these membranes as a promising class of interactive interfaces that may rapidly bring advances in genomics research. Copyright © 2009 Society of Chemical Industry [source]

Design of a pH-sensitive pore-forming peptide with improved performance

CHEMICAL BIOLOGY & DRUG DESIGN, Issue 1 2004
D.H. Haas
Abstract:, GALA is a 30 residue synthetic peptide designed to interact with membranes in a pH-sensitive manner, with potential applications for intracellular drug and gene delivery. Upon reduction of the pH from neutral to acidic, GALA switches from random coil to , -helix, inserts into lipid bilayers, and forms oligomeric pores of defined size. Its simple sequence and well-characterized behavior make the peptide an excellent starting point to explore the effects of sequence on structure, pH sensitivity, and membrane affinity. We describe synthesis and characterization of two derivatives of GALA, termed GALAdel3E and YALA. GALAdel3E has a deletion of three centrally located glutamate residues from GALA, while YALA replaces one glutamate residue with the unusual amino acid 3,5-diiodotyrosine. Both derived peptides retain pH sensitivity, showing no ability to cause leakage of an encapsulated dye from unilamellar vesicles at pH 7.4 but substantial activity at pH 5. Unlike GALA, neither peptide undergoes a conformational change upon reduction of the pH, remaining , -helical throughout. Interestingly, the pH at which the peptides activate is shifted, with GALA becoming active at pH ,5.7, GALAdel3E at pH ,6.2, and YALA at pH ,6.7. Furthermore, the peptides GALAdel3E and YALA show improved activity compared with GALA for cholesterol-containing membranes, with YALA retaining the greatest activity. Improved activity in the presence of cholesterol and onset of activity in the critical range between pH 6 and 7 may make these peptides useful in applications requiring intracellular delivery of macromolecules, such as gene delivery or anti-cancer treatments. [source]