Synthesis of S-Layer Conjugates and Evaluation of Their Modifiability as a Tool for the Functionalization and Patterning of Technical Surfaces

Abstract

Chemical functional groups of surface layer (S-layer) proteins were chemically modified in order to evaluate the potential of S-layer proteins for the introduction of functional molecules. S-layer proteins are structure proteins that self-assemble into regular arrays on surfaces. One general feature of S-layer proteins is their high amount of carboxylic and amino groups. These groups are potential targets for linking functional molecules, thus producing reactive surfaces. In this work, these groups were conjugated with the amino acid tryptophan. In another approach, SH-groups were chemically inserted in order to extend the spectrum of modifiable groups. The amount of modifiable carboxylic groups was further evaluated by potentiometric titration in order to evaluate the potential efficiency of S-layer proteins to work as matrix for bioconjugations. The results proved that S-layer proteins can work as effective matrices for the conjugation of different molecules. The advantage of using chemical modification methods over genetic methods lies in its versatile usage enabling the attachment of biomolecules, as well as fluorescent dyes and inorganic molecules. Together with their self-assembling properties, S-layer proteins are suitable as targets for bioconjugates, thus enabling a nanostructuring and bio-functionalization of surfaces, which can be used for different applications like biosensors, filter materials, or (bio)catalytic surfaces.

<p>Slp-coated liposomes for drug delivery and biomedical applications: potential and challenges</p>

“…Due to its abundant carboxylic and amino groups and its ability to form regular crystalline arrays, Slp has usually been employed to construct a biocatalytic surface for the immobilization of enzymes. 143,144 Immobilized enzymes have significant economic value in the pharmaceutical industry. The immobilization of enzymes can facilitate the separation and reuse of enzymes, thus reducing the cost of industrial production.…”

Insights into Ionizing-Radiation-Resistant Bacteria S-Layer Proteins and Nanobiotechnology for Bioremediation of Hazardous and Radioactive Waste

“…[72,73]. The segments at the outermost surface of SLPs are harboring -COOH, -OH, and -NH 2 groups [74]. In addition, using analyses of post-translational modifications, it was highlighted that SLPs can be phosphorylated [10].…”

Analysis of self-assembly of S-layer protein slp-B53 from Lysinibacillus sphaericus

“…In this work, several complementary analytical techniques and methods have been applied to examine structure-function relationships and dynamics for assembly of S-layer protein 1 3 2015; Baranova et al 2012). In general, S-layer proteins self-assemble to two-dimensional (2D) crystals (Györvary et al 2003;Sára and Sleytr 2000;Sleytr et al 1999;Pum et al 1989;Sleytr 1975;Weinert et al 2015), thereby providing the primary protective barrier for prokaryotic cells. S-layers can be regarded as the simplest protein membrane (Engelhardt 2007;Kern et al 2011;Schuster and Sleytr 2009).…”