title: The formation of amyloid-like fibrils of α-chymotrypsin in different aqueous organic solvents.
abstract: The formation of amyloid-like fibrils of α-chymotrypsin was studied in aqueous ethanol, methanol, tertbutanol, dimethylformamide and acetonitrile. Thioflavin T (ThT), Congo red (CR) and 1-anilino-8-naphthalenesulfonic acid (ANS) binding, turbidity, intrinsic fluorescence and far-UV circular dichroism measurements were employed to characterize the amyloid fibril formation. The greatest extent of fibril formation after incubation for 24 h at pH 7.0 and at 24 °C was in ethanol at 55%, in methanol and dimethylformamide (DMF) at 60-70% and in tert-butanol at 60-80%. The ANS binding and intrinsic fluorescence results showed that the hydrophobic residues are more solvent-exposed in the aggregated form of α-chymotrypsin. The ThT, CR binding and far-UV CD measurements indicated that the formation of the cross-β structure of α-chymotrypsin depends on the polarity of the organic solvent. To determine the role of surface charges in the aggregation, chemically modified forms of α-chymotrypsin were prepared. The citraconylated and succinylated enzymes exhibited a higher and the enzyme forms modified with aliphatic aldehydes a lower propensity for aggregation. These results suggest the important role of surface charges in the aggregation of α-chymotrypsin.
authors.affiliation: Department of Biochemistry and Molecular Biology, Faculty of Science and Informatics, University of Szeged, H-6726 Szeged, Középfasor 52, Hungary.
authors.forename: L Mária
authors.initials: LM
authors.lastname: Simon
authors.forename: Ilona
authors.initials: I
authors.lastname: Laczkó
authors.forename: Anett
authors.initials: A
authors.lastname: Demcsák
authors.forename: Dávid
authors.initials: D
authors.lastname: Tóth
authors.forename: Marta
authors.initials: M
authors.lastname: Kotormán
authors.forename: Lívia
authors.initials: L
authors.lastname: Fülöp
mesh_terms: D000682:Amyloid / Q000737:chemistry* / Q000378:metabolism; D058227:Amyloidogenic Proteins / Q000737:chemistry; D002918:Chymotrypsin / Q000737:chemistry* / Q000378:metabolism; D002942:Circular Dichroism; D003224:Congo Red; D009930:Organic Chemicals / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet
chemical_list: D000682:Amyloid; D058227:Amyloidogenic Proteins; D009930:Organic Chemicals; D012997:Solvents; D003224:Congo Red; D002918:Chymotrypsin; C117608:alpha-chymotrypsin