title: Formation of heat-induced cottonseed congossypin(7S) fibrils at pH 2.0.
abstract: BACKGROUND
  Heat-induced protein aggregation is important for the texture of various food products. Many types of food proteins have been found to assemble into fibrillar structures under certain conditions. We studied fibril formation of cottonseed 7S storage protein upon heating (for 0-720 min) at 90°C and pH 2.0, investigated the conversion rate, and determined the extent of thermal aggregation.
  
  
  RESULTS
  Thioflavin-T fluorescence and Congo-red analysis indicated the formation of amyloid-like fibrils upon heating. Centrifugal filtration indicated that the conversion was very low (<10%) until congossypin concentration up to 2 mg mL(-1), and the conversion increases with increasing heating time, but levels off after longer heating times. Dynamic light scattering and atomic force microscopy showed that the extent of thermal aggregation at pH 2.0, or contour length of the worm-like and fine-stranded aggregates, progressively increased with increasing heating time. Furthermore, reducing electrophoresis analyses indicated that progressive polypeptide hydrolysis occurred upon heating. Experiments indicate that congossypin can form heat-induced amyloid-like aggregates and the conversion of congossypin monomers into fibrils increased with heating time and protein concentration.
  
  
  CONCLUSIONS
  The results would be of vital importance for the utilisation of cottonseed proteins to produce thermally induced fibrillar gels with excellent properties.
authors.affiliation: State Key Laboratory of Food Science and Technology and School of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi, 214122, People's Republic of China.
authors.forename: Jian-Zhong
authors.initials: JZ
authors.lastname: Zhou
authors.forename: Hui
authors.initials: H
authors.lastname: Zhang
authors.forename: Hai-Yan
authors.initials: HY
authors.lastname: Yang
authors.forename: Li
authors.initials: L
authors.lastname: Wang
authors.forename: Hai-Feng
authors.initials: HF
authors.lastname: Qian
mesh_terms: D000682:Amyloid; D005524:Food Technology; D005782:Gels; D003368:Gossypium / Q000737:chemistry*; D006358:Hot Temperature; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D010940:Plant Proteins / Q000737:chemistry*; D012639:Seeds / Q000737:chemistry*
chemical_list: D000682:Amyloid; D005782:Gels; D010940:Plant Proteins
keywords: amyloid fibrils; assembly; congossypin(7S); cottonseed protein; heat-induced aggregation