Abstract
Protein secondary structure changes by low-energy ion irradiation are reported for the first time. The selected system is 30
keV N
+ irradiation on bovine serum albumin (BSA). After irradiation at increasing fluences from 1.0×10
15 to 2.5×10
16
ion/cm
2, Fourier transform infrared spectra analysis was conducted. It was found that the secondary structures of BSA molecules were very sensitive to ion irradiation. Secondary conformations showed different trends of change during irradiation. With the increase of ion fluence from 0 to 2.5×10
16
ion/cm
2, the fraction of
α-helix and
β-turns decreased from 17 to 12%, and from 40 to 31%, respectively, while that of random coil and
β-sheet structure increased from 18 to 27%, and from 25 to 30%, respectively. Possible explanations for the secondary conformational changes of protein are proposed.