Protein interactions with ordered lipid films: Specific and unspecific binding

Abstract

Interactions of proteins with membranes are of importance in many fields of biochemistry and In particular, studying membrane-bound receptors in vitro requires working models for biological membranes. As a model for lipid membranes, monolayers of amphiphiles on an aqueous subphase, or mono-and multilayers of amphiphiles on solid substrates (Langmuir-Blodgett films) are often used. An evaluation of specific and unspecific interactions of polypeptides with several types of films is discussed in this paper.Proteins can exhibit several modes of interaction with the hydrophilic or the hydrophobic sites of lipid-covered surfaces: these can be, for example, ionic interactions with the charged hydrophilic head groups of lipids, that may eventually lead to an intercalation of the proteins into the lipid layer between their hydrophobic tails. Proteins are also well known to adsorb on hydrophobic surfaces, and so it is to be expected that they do on Langmuir-Blodgett films.Furthermore, a specific interaction of proteins with lipid monolayers can be demonstrated when functionalized lipids are used. A very intelligent sensor mimicking a biological function could exist in a lipid film containing molecules with

Chromatic Transitions in Polydiacetylene Langmuir‐Blodgett Films due to Molecular Recognition at the Film Surface Studied by Spectroscopic Methods and Surface Analysis

“…Substantial buffer-induced color changes (CR 1 > 20%) were observed in the PDA films after immersion in tris(hydroxymethyl)aminomethane hydrochloride in a 0.5 M or 0.1 M NaCl solution as well as in undiluted and diluted phosphate-buffered saline solution. The addition of NaCl and/or KCl to these solutions is very often recommended in the literature concerned with the non-affinity binding of the proteins avidin or streptavidin to biotin , [11,22,23] but shows significant interference with the PDA films, which are sensitive to high ionic strengths.…”

“…[23] The strain induced into the film by conformational changes as a result of molecular recognition is transferred to the polydiacetylene assembly with the consequence of distorting the supramolecular conjugated p-electron system.…”

Ultrathin organic films: Molecular Architectures for advanced optical, electronic and bio‐related systems

“…In addition, biocompatibility may be provided. [31] 0 Precise orientation of the monolayer configuration with specific binding sites to maximize the access of reactive species in the sensor compartment. 0 The overall thickness reduced to molecular dimensions should lead to very short response times because equilibria across such ultrathin films are thought to be faster…”

The influence of hydrophilic spacers on the phase behavior of ether lipids

“…They play an important role in coupling mechanisms at surfaces and interfaces. In the system Streptavidin/Biotin the lateral protein density is mainly dependent on the length of the spacer between the biotin and the hydrophobic anchor of the functionalized lipid [11][12][13].…”