Salt-Induced Aggregation of Lysozyme Studied by Cross-Linking with Glutaraldehyde: Implications for Crystal Growth

Wang, F.; Hayter, John B.; Wilson, Lori J.

doi:10.1107/s0907444996005227

Cited by 17 publications

(16 citation statements)

References 11 publications

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“…Amyloid aggregation in this model is accelerated as lysozyme becomes unfolded at 55C and peaks at 65C before amorphous aggregation becomes the dominate pathway [10]. Salt concentration has been shown to strongly influence the aggregation of lysozyme [11]–[13]; we therefore examined lysozyme aggregation under a range of salt concentrations. We then considered the potential effects of amyloid gel formation on intra- and extracellular transport.…”

Section: Introductionmentioning

confidence: 99%

Gel Formation in Protein Amyloid Aggregation: A Physical Mechanism for Cytotoxicity

et al. 2014

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Amyloid fibers are associated with disease but have little chemical reactivity. We investigated the formation and structure of amyloids to identify potential mechanisms for their pathogenic effects. We incubated lysozyme 20 mg/ml at 55C and pH 2.5 in a glycine-HCl buffer and prepared slides on mica substrates for examination by atomic force microscopy. Structures observed early in the aggregation process included monomers, small colloidal aggregates, and amyloid fibers. Amyloid fibers were observed to further self-assemble by two mechanisms. Two or more fibers may merge together laterally to form a single fiber bundle, usually in the form of a helix. Alternatively, fibers may become bound at points where they cross, ultimately forming an apparently irreversible macromolecular network. As the fibers assemble into a continuous network, the colloidal suspension undergoes a transition from a Newtonian fluid into a viscoelastic gel. Addition of salt did not affect fiber formation but inhibits transition of fibers from linear to helical conformation, and accelerates gel formation. Based on our observations, we considered the effects of gel formation on biological transport. Analysis of network geometry indicates that amyloid gels will have negligible effects on diffusion of small molecules, but they prevent movement of colloidal-sized structures. Consequently gel formation within neurons could completely block movement of transport vesicles in neuronal processes. Forced convection of extracellular fluid is essential for the transport of nutrients and metabolic wastes in the brain. Amyloid gel in the extracellular space can essentially halt this convection because of its low permeability. These effects may provide a physical mechanism for the cytotoxicity of chemically inactive amyloid fibers in neurodegenerative disease.

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Section: Introductionmentioning

confidence: 99%

Gel Formation in Protein Amyloid Aggregation: A Physical Mechanism for Cytotoxicity

et al. 2014

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“…The ability of lysozyme to oligomerize is worth mentioning in this context. It self-associates to dimers, trimers and tetramers in the pH region from ∼4 to 10, and to larger aggregates at pH > ∼10 [44][45][46][47][48]. This oligomerization increases with protein concentration and with ionic strength [49].…”

Section: Lysozyme Distributionmentioning

confidence: 99%

Interaction between lysozyme and poly(acrylic acid) microgels

Johansson

Hansson

Malmsten

2007

Journal of Colloid and Interface Science

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“…They found the largest identifiable species in solution to be an octamer. Covalent cross-linking followed by SDS-PAGE separation has recently been used to detect aggregates of lysozyme in high ionic strength solutions with the largest identifiable species being a tetramer (Wang et al, 1996).…”

Section: Introductionmentioning

confidence: 99%

Monomer concentrations and dimerization constants in crystallizing lysozyme solutions by dialysis kinetics

Wilson

Adcock-Downey

Pusey

1996

Biophysical Journal

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Dialysis kinetics measurements have been made to study the effect of ionic strength on the dimerization of lysozyme in acidic solutions that lead to the growth of tetragonal lysozyme crystals. Using glutaraldehyde cross-linked dimers of lysozyme, we have determined that both monomers and dimers can escape from 25,000 molecular weight cutoff dialysis membranes with velocity constants of 5.1 x 10(-7) and 1.0 x 10(-7) s(-1) for the monomer and dimer species, respectively. The flux from 25K MWCO membranes has been measured for lysozyme in pH 4.0 buffered solutions of 1, 3, 4, 5, and 7% NaCl over a wide range of protein concentrations. Assuming that dimerization is the first step in crystallization, a simple monomer to dimer equilibrium was used to model the flux rates. Dimerization constants calculated at low protein concentrations were 265, 750, 1212, and 7879 M(-1) for 3, 4, 5, and 7% NaCl, respectively. These values indicate that dimerization increases with the ionic strength of the solution suggesting that aggregation is moderated by electrostatic interactions. At high protein concentrations and high supersaturation, the dimerization model does not describe the data well. However, the Li model that uses a pathway of monomer <-> dimer <-> tetramer <-> octamer <-> 16-mer fits the measured flux data remarkably well suggesting the presence of higher order aggregates in crystallizing solutions.

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Salt-Induced Aggregation of Lysozyme Studied by Cross-Linking with Glutaraldehyde: Implications for Crystal Growth

Cited by 17 publications

References 11 publications

Gel Formation in Protein Amyloid Aggregation: A Physical Mechanism for Cytotoxicity

Gel Formation in Protein Amyloid Aggregation: A Physical Mechanism for Cytotoxicity

Interaction between lysozyme and poly(acrylic acid) microgels

Monomer concentrations and dimerization constants in crystallizing lysozyme solutions by dialysis kinetics

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