Spectroscopic study on the effect of crystallization of the hydroxyapatite on the secondary structure of bovine serum albumin

The effect of crystallization of hydroxyapatite on the secondary structure of bovine serum albumin(BSA) was studied by circular dichroism spectrum, Fourier transform infrared spectroscopy, derivative, deconvolution and curve-fitting techniques in the present paper. The CD results show that pure bovine serum albumin is composed of 56.8% alpha-helices, 5.8% beta-sheets, 14.1% beta-turns and 23.9% random structures, while the bovine serum albumin in the Ca-10 (PO4)(6) (OH)(2)/bovine serum albumin solution is composed of 25.4% alpha-helices, 25.0% beta-sheets, 20.0% beta-turns and 29.7% random structures. The results of Fourier transform infrared spectroscopy are in good agreement with those from the CD spectra. From these results it can be seen that the percentage of alpha-helix decreased, while that of the beta-sheet increased with the formation of the crystal of hydroxyapatite, and with the reaction time increasing, the percentages of alpha-helix obviously dropped and those of beta-sheet markedly rose. These results showed that alpha-helix transformed into beta-sheet. Furthermore the essence of these changes is discussed.