Fibrillized structure

Shiv]i A P, Brown F, Davies M C, Jennings K H, Roberts C J, Tendler S J B, Wilkinson M J and Williams P M 1995 Scanning tunnelling microscopy studies of p-amyloid fibril structure and assembly FEBS Lett. 371 25-8... 

Fluorescently modified fibrils are a useful probe. Furthermore, MacPhee and Dobson have shown that it may be possible to bind other non-peptidic functional groups, provided they can be covalently linked during synthesis. They also demonstrate that utilizing intrinsic fibril structural features might be one approach to the production of peptide scaffolds with well-defined ligand spacings. 

Fig. 29 Fractured morphology of spherulitic objects in a thin film of PET crystallized at 220 °C [36]. On the fractured surface many small particles with a diameter of 0.2 0.3 xm are seen while on the spherulite surface there is a fibril structure 0.2 05 xm thick... 

Wang, J., Gulich, S., Bradford, C., Ramirez-Alvarado, M., and Regan, L. (2005). A twisted four-sheeted model for an amyloid fibril. Structure 13, 1279-1288. 

In view of the consideration that /(-solenoids and /(-arcades may also be structural elements of amyloid fibrils (Kajava et al., 2004 Lazo and Downing, 1998 Margittai and Langen, 2004 Pickersgill, 2003), sequence-based detection and structure prediction of /(-solenoid proteins are pertinent to the identification of amyloidogenic sequences and the elucidation of amyloid fibril structures. As with /(-solenoid domains, amyloidogenic regions of... 

Wetzel, R. (2002). Ideas of order for amyloid fibril structure. Structure 10, 1031. 

Tuite, M. F. (2000). Yeast prions and their prion-forming domain. Cell 100, 289-292. Tycko, R. (2000). Solid-state NMR as a probe of amyloid fibril structure. Curr. Opin. Chem. Biol. 4, 500-506. 

Inouye, H., and Kirschner, D. A. (1996). Refined fibril structures The hydrophobic core in Alzheimer s amyloid /1-protein and prion as revealed by X-ray diffraction. Ciba Found. Symp. 199, 22-35 discussion 35-9. 

Unfortunately, the description of amyloid fibrils given above is simplistic since in vitro self-assembly of amyloid peptides and proteins yields polymorphic structures, as has been commonly observed in the past for other protein assemblies such as actin filaments (Millonig et al, 1988) and intermediate filaments (Herrmann and Aebi, 1999). On the one hand, assembly polymorphism complicates the characterization of fibril structure. On the other hand, it offers some insight into fibril formation. For this reason a more rational understanding of amyloid fibril formation at the molecular level is a key issue in the field of amyloidosis. 

Serpell, L. C. (2000). Alzheimer s amyloid fibrils Structure and assembly. Biochim. Biophys. Acta 1502, 16-30. 

The notion of a common core structure has been further supported by synchrotron X-ray fiber diffraction patterns of several amyloid fibrils the patterns show common reflections in addition to those at 4.7 and 10 A (Sunde et al., 1997). Although these data give some insight into the arrangement of the amyloid fibril core, the exact molecular structure and organization of the proteins making up this common core have yet to be uniquely defined. The inherently noncrystalline, insoluble nature of the fibrils makes their structures difficult to study via traditional techniques of X-ray crystallography and solution NMR. An impressive breadth of biochemical and biophysical techniques has therefore been employed to illuminate additional features of amyloid fibril structure. 

The resultant data have led to the proposal of numerous molecular models of amyloid fibril structure (Makin and Serpell, 2005). These models can be separated into three general classes (Fig. 2) (1) the Refolding models,... 

A cross-jS spine model was proposed for the fibril structure of human /]2-microglobulin (h/]2m) (Ivanova et al., 2004). h/I2m is a 99-amino acid serum protein with a 7-stranded /(-sandwich fold (Fig. 10A Saper et al, 1991). In patients on long-term kidney dialysis, the protein is deposited as amyloid fibrils in the joints (Floege and Ehlerding, 1996 Koch, 1992). In vitro-formed fibrils of h/)2m give a cross-/] X-ray diffraction pattern (Ivanova et al., 2004 Smith et al., 200S). Several studies have shown that segments of h/]2m form amyloid-like fibrils on their own (Ivanova et al., 2003 Jones et al., 2003 Kozhukh et al, 2002). 

Fay et al. (2005) have proposed a completely different model for Ure2p fibril structure. Their model is based on data which suggest that Ure2p fibrils do not have a cross-/ structure (Bousset et al., 2003) and that the C-terminal globular domain is tightly involved in the fibrillar scaffold (Bousset et al.,... 

Lazar KL, Miller-Auer H, Getz GS, Orgel JPRO, Meredith SC. HeUx-tum-heUx peptides that form a-helical fibrils turn sequences drive fibril structure. Biochemistry 2005 44 12681-12689. 

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