Degradation of human serum albumin by infrared free electron laser enhanced by inclusion of a salen-type schiff base Zn (II) complex

Yuika Onami, Takayasu Kawasaki, Hiroki Aizawa, Tomoyuki Haraguchi, Takashiro Akitsu, Koichi Tsukiyama, Mauricio A. Palafox

Research output: Contribution to journalArticle


A salen-type Schiff base Zn(II) complex included in human serum albumin (HSA) protein was examined by UV-Vis, circular dichroism (CD), and fluorescence (PL) spectra. The formation of the composite material was also estimated by a GOLD program of ligand–protein docking simulation. A composite cast film of HSA and Zn(II) complex was prepared, and the effects of the docking of the metal complex on the degradation of protein molecules by mid-infrared free electron laser (IR-FEL) were investigated. The optimum wavelengths of IR-FEL irradiation to be used were based on experimental FT-IR spectra and vibrational analysis. Using TD-DFT results with 6-31G(d,p) and B3LYP, the IR spectrum of Zn(II) complex could be reasonably assigned. The respective wavelengths were 1652 cm−1 (HSA amide I), 1537 cm−1 (HSA amide II), and 1622 cm−1 (Zn(II) complex C=N). Degradation of HSA based on FT-IR microscope (IRM) analysis and protein secondary structure analysis program (IR-SSE) revealed that the composite material was degraded more than pure HSA or Zn(II) complex; the inclusion of Zn(II) complex enhanced destabilization of folding of HSA.

Original languageEnglish
Article number874
JournalInternational journal of molecular sciences
Issue number3
Publication statusPublished - 1 Feb 2020



  • Fluorescence
  • Human serum albumin
  • IR-FEL
  • Schiff base
  • TD-DFT
  • Zn(II) complex

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