title: A comparative study on the aggregating effects of guanidine thiocyanate, guanidine hydrochloride and urea on lysozyme aggregation.
abstract: Protein aggregation and its subsequent deposition in different tissues culminate in a diverse range of diseases collectively known as amyloidoses. Aggregation of hen or human lysozyme depends on certain conditions, namely acidic pH or the presence of additives. In the present study, the effects on the aggregation of hen egg-white lysozyme via incubation in concentrated solutions of three different chaotropic agents namely guanidine thiocyanate, guanidine hydrochloride and urea were investigated. Here we used three different methods for the detection of the aggregates, thioflavin T fluorescence, circular dichroism spectroscopy and atomic force microscopy. Our results showed that upon incubation with different concentrations (0.5, 1.0, 2.0, 3.0, 4.0, 5.0M) of the chemical denaturants, lysozyme was aggregated at low concentrations of guanidine thiocyanate (1.0 and 2.0M) and at high concentrations of guanidine hydrochloride (4 and 5M), although no fibril formation was detected. In the case of urea, no aggregation was observed at any concentration.
authors.affiliation: Department of Biological Sciences, Institute in Advanced Studies in Basic Sciences (IASBS), Zanjan, Iran. Electronic address: emadi@iasbs.ac.ir.
authors.forename: Saeed
authors.initials: S
authors.lastname: Emadi
authors.affiliation: Department of Biological Sciences, Institute in Advanced Studies in Basic Sciences (IASBS), Zanjan, Iran.
authors.forename: Maliheh
authors.initials: M
authors.lastname: Behzadi
mesh_terms: D002942:Circular Dichroism; D019791:Guanidine / Q000737:chemistry*; D006146:Guanidines / Q000737:chemistry*; D018625:Microscopy, Atomic Force; D009113:Muramidase / Q000737:chemistry*; D011485:Protein Binding; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D013861:Thiocyanates / Q000737:chemistry*; D014508:Urea / Q000737:chemistry*
chemical_list: D006146:Guanidines; D013861:Thiocyanates; C054436:guanidine thiocyanate; D014508:Urea; D009113:Muramidase; D019791:Guanidine
keywords: Aggregation; Fibrillation; Guanidine hydrochloride; Guanidine thiocyanate; Lysozyme; Urea