In vitro creation of amyloid fibrils from native and Arg124Cys mutated beta IGH3((110-131)) peptides, and its relevance for lattice corneal amyloid dystrophy type I

beta IGH3 protein has been recently involved in the pathogenesis of blindin g corneal diseases, some of which have characteristic amyloid corneal depos its. The 124 codon of the beta ig-h3 gene seems to be crucial for the amylo idogenicity of the protein product. We presently report an in vitro system that reproducibly forms amyloid fibrils from beta IGIH3((110-131)) derived peptides. We also assessed the differences in fibril formation of two 22-am ino acid peptides centered on the 124 residue: the native form and the Arg1 24Cys peptide (mutation linked to lattice corneal amyloid dystrophy type 1) . After dialysis of Arg124Cys peptide against PBS 1/15 M pH 7.4 for 72 hour s, Congo red staining and electron microscopy demonstrated the presence of abundant material fulfilling the criteria of amyloid. Quantitative analysis with thioflavine T fluorescence studies confirmed the high capacity of Arg 124Cys peptide to form amyloid fibrils when compared to the native form. (C ) 2000 Academic Press.