Collagen of porcine auricle has unique biochemical and biophysical characteristics

Collagen is a major component of the extracellular matrix and is used as a material in tissue engineering. We demonstrated the extraction of atelocollagen from porcine auricular and characterized its unique physical and biochemical properties. Extracted type I collagens of auricular collagen using acetic acid and pepsin (PAC) showed superior fibrillogenesis and viscoelasticity compared to type I collagen from porcine skin. The observation of PAC fibrils by transmission electron microscopy and Atomic Force Microscope under physiological conditions revealed long fibrils with pronounced 3D structures, while type I collagen from porcine skin revealed a flat structure. Furthermore, a PAC-coated plate promoted higher cell proliferation than when grown on a skin type I collagen-coated plate. Porcine auricular type I collagen has superior biophysical and biological properties in terms of viscoelasticity, fibrillogenesis, and cell proliferation, and can be used in further studies toward novel potential applications in the field of medical materials.     

Amyloidogenic Protein–Membrane Interactions: Mechanistic Insight from Model Systems

The toxicity of amyloid‐forming proteins is correlated with their interactions with cell membranes. Binding events between amyloidogenic proteins and membranes result in mutally disruptive structural perturbations, which are associated with toxicity. Membrane surfaces promote the conversion of amyloid‐forming proteins into toxic aggregates, and amyloidogenic proteins, in turn, compromise the structural integrity of the cell membrane. Recent studies with artificial model membranes have highlighted the striking resemblance of the mechanisms of membrane permeabilization of amyloid‐forming proteins to those of pore‐forming toxins and antimicrobial peptides.     

Reduction of conformational mobility and aggregation in W60G β2‐microglobulin: assessment by 15N NMR relaxation

The amyloid pathology associated with long‐term haemodialysis is due to the deposition of β₂‐microglobulin, the non‐polymorphic light chain of class I major histocompatibility complex, that accumulates at bone joints into amyloid fibrils. Several lines of evidence show the relevance of the tryptophan residue at position 60 for the fibrillogenic transition of the protein. A comparative ¹⁵N NMR relaxation analysis is presented for wild‐type human β₂‐microglobulin and W60G β₂‐microglobulin, i.e. the mutant with a glycyne replacing the natural tryptophan residue at position 60. The experimental data, collected at 11.4 T and 310 K, were analyzed by means of the reduced spectral density approach. Molecular dynamics (MD) simulations and corresponding thermodynamic integration, together with hydrodynamic calculations were performed to support data interpretation. The analysis results for the mutant protein are consistent with a reduced aggregation with respect to the wild‐type counterpart, as a consequence of an increased conformational rigidity probed by either NMR relaxation and MD simulations. Although dynamics in solution is other than fibrillar competence, the assessed properties of the mutant protein can be related with its reduced ability of forming fibrils when seeded in 20% trifluoroethanol. Copyright © 2013 John Wiley & Sons, Ltd.