Self-assembled protein fibers

Ryadnov MG, Woolfson DN. Engineering the morphology of a self-assembling protein fiber. Nat Mater 2003a 2 329-332. 

Smith AM, BanweU EE, Edwards WR, Pandya MJ, Woolfson DN. Engineering increased stability into self-assembled protein fibers. Adv Funct Mater 2006 16 1022-1030. 

The first elastomeric protein is elastin, this structural protein is one of the main components of the extracellular matrix, which provides stmctural integrity to the tissues and organs of the body. This highly crosslinked and therefore insoluble protein is the essential element of elastic fibers, which induce elasticity to tissue of lung, skin, and arteries. In these fibers, elastin forms the internal core, which is interspersed with microfibrils [1,2]. Not only this biopolymer but also its precursor material, tropoelastin, have inspired materials scientists for many years. The most interesting characteristic of the precursor is its ability to self-assemble under physiological conditions, thereby demonstrating a lower critical solution temperature (LCST) behavior. This specific property has led to the development of a new class of synthetic polypeptides that mimic elastin in its composition and are therefore also known as elastin-like polypeptides (ELPs). 

Porphyrin-based self-assembled molecular squares 389 can form mesoporous thin films in which the edge of a square, thus the size of the cavity, can be adjusted by appropriate choice of substituents [8]. Fibers that form coil-coiled aggregates with distinct, tunable helicity are built from crown ethers bearing porphyrins 390 [9]. In addition to the porphyrin applications discussed in Sections 6.3.2.2 and 6.4, dendrimer metalloporphyrins 391 to be applied in catalysis [10] and the water-soluble dendritic iron porphyrin 319 modelling globular heme proteins [11] can be mentioned. 

This chapter describes the self-assembly of non-native protein fibers known as amyloid fibrils and the development of these fibrils for potential applications in nanotechnology and biomedicine. It extends an earlier review by the author on a related topic (Gras, 2007). In Section 1, the self-assembly of polypeptides into amyloid fibrils and efforts to control assembly and any subsequent disassembly are discussed. In Section 2, this review focuses on the important role of surfaces and interfaces during and after polypeptide assembly. It examines how different surfaces can influence fibril assembly, how surfaces can be used to direct self-assembly in order to create highly ordered structures, and how different techniques can be used to create aligned and patterned materials on surfaces following self-assembly. 

Section 2.1 above). These functional fibrils suggest that designed fibrils can be developed as compatible materials. Toxicology will be a potential issue for all structures that self-assemble on a nanoscale. However, the natural building blocks used to construct protein fibers may increase the biocompatibility of these structures compared to other man-made materials. Polypeptide self-assembly also represents a route for generating ECM-like structures that are not only simpler than their natural equivalents but also easier to prepare. 

In a systematic study, the relationship between structure acquisition and self-assembly in NM fibrillization reactions was monitored through a series of biochemical and microscopic probes (Fig. 2) (Serio et al., 2000). Under these conditions, the conformational transition could not be temporally separated from self-assembly of NM. That is, the protein adopts the /1-rich structure as it assembles into fibers. The concentration dependences of the lag and assembly phases were also assessed in this study as an indirect measure of the relationship between conformational conversion and self-association. The results were consistent with a /1-rich structure s being conferred to protein concomitant with assembly (Serio et al., 2000 DePace et al., 1998). 

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