Structural transition of human calcitonin and molecular mechanism of fibrillization

2000 Fiscal Year Final Research Report Summary

• Project/Area Number: 11680654
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Biophysics
• Research Institution: Nagaoka Universsity of Technology
• Principal Investigator: SODA Kunitsugu Nagaoka Universsity of Technology, Faculty of Engineering, 工学部, 教授 (10011686)
• Project Period (FY): 1999 – 2000
• Keywords: calcitonin / hexafluoro-isopropanol / amyloid / protein aggregation / fibrillization / solution x-ray scattering / structural transition

Research Abstract

Dependence of the structure and aggregation of human calcitonin(hCT) on pH and concentration of alcohol, especially of hexafluoro-2-propanol (HFIP), in solution was examined by various biophysical methods. The structure of hCT in solution with a concentration of 20 μg/ml was surveyed against pH and HFIP concentration. Four structural states could be identified as the random coil, the α-helical monomer, the α-helical oligomer, and the amyloid-like aggregate. Addition of a moderate amount of HFIP was found to have remarkable effects on the aggregation of hCT. At pH【greater than or equal】4.8, aggregates are formed very rapidly in solution with a medium concentration of HFIP : At pH 7, they are formed within only several minutes after dissolving hCT in solution with 5-15% HFIP. This results from the combined effects that (1)intermolecular Coulombic repulsive forces are reduced due to decrease in the net charge on hCT, (2)addition ofa moderate concentration of HFIP stabilizes the α-helical structure of hCT necessary to initiate aggregation, but (3)resultant α-helical oligomers are not stabilized excessively so that they can be easily converted to larger aggregates. Conversely, in a neutral solution not containing HFIP, it takes more than an hour for hCT to form fibrillar aggregates even at a very high hCT concentration of 10mg/ml.

Research Products

• [Journal Article] The compact and expanded denatured conformations of apomyoglobin in the methanol-water solvent (1999)
  • Author(s): Kamatari, Y.O, 0hji, S, Konno, T, Seki, Y, Soda, K, Kataoka, M, Akasaka, K
  • Journal Title: Protein Science 8 Pages: 873-882
  • Description: 「研究成果報告書概要(和文)」より
• [Journal Article] The compact and expanded denatured conformations of apomyoglobin in the methanol-water solvent (1999)
  • Author(s): Kamatari, Y.O., Ohji, S., Konno, T., Seki, Y., Soda, K., Kataoka, M., Akasaka, K.
  • Journal Title: Protein Science 8 Pages: 873-882
  • Description: 「研究成果報告書概要(欧文)」より
• [Journal Article] Nonnative structure of proteins and implications for protein folding (1999)
  • Author(s): Soda, K., Seki, Y.
  • Journal Title: old and New Views of Protein Folding Pages: 41-50
  • Description: 「研究成果報告書概要(欧文)」より
• [Book] Nonnative structure of proteins and implications for protein folding, in "0ld and New Views of Protein Folding" (1999)
  • Author(s): Soda, K, Seki, Y.
  • Total Pages: 41-50
  • Publisher: Kuwajima,K.,and Arai, M.ed.,Elsevier
  • Description: 「研究成果報告書概要(和文)」より