Fibril growth

Shen CL, Scott GL, Merchant F, Murphy RM. Light scattering analysis of fibril growth from the amino-terminal fragment beta(l-28) of beta-amyloid peptide. Biophys J 1993 65 2383-2395. 

Ban T, Hamada D, Hasegawa K, Naiki H, Goto Y (2003) Direct observation of amyloid fibril growth monitored by thioflavin T fluorescence. J Biol Chem 278(19) 16462-16465... 

This change in scale and interaction regimes would form the basis to differentiate spinning from fibril growth. This is particularly a propos from a materials point of view, where a multifibrillar composition offers a mechanical advantage over a single fiber of the same cross-sectional area (Putthanarat et al., 2000). 

Col Hal null mice have fibril diameter abnormalities in the early postnatal stage but the adult showed no significant differences. Type XIV collagen might function early in development regulating the entry of fibril intermediates into lateral fibril growth. ... 

VIII. Factors that May Regulate Fibril Growth and Size. 357... 

Sechler, J. L., Rao, H., Cumiskey, A. M., Vega-Colon, I., Smith, M. S., Murata, T., and Schwarzbauer, J. E. (2001). A novel fibronectin binding site required for fibronec-tin fibril growth during matrix assembly./ Cell Biol. 154, 1081-1088. 

Fibril formation is a nucleated process that is characterized by an initial lag phase (Devlin et al., 2006 Hortschansky et al., 2005). Nucleation is followed by a fibril growth phase known as elongation. The assembly kinetics then plateau as the majority of polypeptide is incorporated into fibrillar structures. The final portion of polypeptide incorporated into fibrils is characteristic to a particular fibril system and can vary from low conversions to greater than 99% of all protein in the sample (Gras et al., 2008). 

Seeding is one way of potentially controlling what is typically an uncontrolled fibril assembly process, where polypeptide building blocks are combined in solution under favorable conditions. Seeds are short fibril fragments that can nucleate fibril growth, eliminate the lag phase, and... 

Mica modified Positively charged Recombinant (32-microglobulin Fibril growth observed Relini et al. (2006)... 

Surfaces can do more than stimulate the growth of amyloid fibrils the presence of a surface during assembly can also influence fibril morphology. Fibril diameter has been observed to be smaller on surfaces than in the bulk for some polypeptide systems (Zhu et al., 2002). This may be due to the constraints imposed by the surface or could result from a different mechanism of fibril growth. The shape of fibrils formed on surfaces can also differ to the shape of fibrils formed in the bulk solution. 

Figure 5.3. Turbidity-time curve illustrating collagen self-assembly.Turbidity-time curve illustrating lag phase, during which small linear and lateral aggregates form, and growth phase, during which unit fibers form that rapidly grow into fibers. The plateau is characteristic of termination of fibril growth.

Fig. 14.7. Effect of UV-exposure on seeded amyloid fibril formation in prion protein, P2-microglobulin and a-synuclein. Samples of unexposed (filled square) and UV-exposed (filled circle) (a) 1 mg ml-1 prion protein in 20 mM sodium phosphate buffer (pH 6.8) containing 100 mM NaCl, 3M urea and 1M GdmCl, (b) 0.5 mg ml-1 P2-microglobulin in 50 mM citrate buffer (pH 2.5) containing 100 mM KC1 and (c) a-synuclein in 20 mM HEPES-NaOH buffer (pH 7.0) containing 100 mM NaCl and 0.5 mM SDS, were treated with the respective sonicated fibril seeds, and the fibril growth was monitored with time by ThT fluorescence...

Our study shows that UV exposure of prion protein, P2-microglobulin and a-synuclein leads to loss of ability of these proteins to form amyloid fibrils de novo. However, they retained the ability to elongate the fibrils when provided with preformed fibrils as seeds. Thus, UV exposure selectively compromises the ability to nucleate fibril growth. 

Real-Time Observation of Amyloid Fibril Growth by Total Internal Reflection Fluorescence Microscopy... 

To obtain further insight into the structure and heterogeneity of amyloid fibrils, direct observation of individual fibrils is important. Here we describe a unique approach we developed to monitor fibril growth in real time at the single fibril level [13-17]. On the basis of the observed dramatic diversity and underlying structural basis, we classify amyloid supramolecular assemblies [18],... 

Fig. 15.2. Direct observation of (32-m amyloid fibril growth obtained by TIRFM. Adapted from ref. [13] with permission. Incubation times are 0, 30, 60, and 90 min...

Fig. 15.3. Direct observation of AP(l-40) amyloid fibril growth by TIRFM. Realtime monitoring of fibril growth on glass slides. Arrows indicate the unidirectional growth of A (i from a single seed fibril. The scale bar represents 10 pm. Reproduced from [14] with permission...

---