Study on effect of lipophilic curcumin on sub-domain IIA site of human serum albumin during unfolded and refolded states: A synchronous fluorescence spectroscopic study

详细信息	查看全文 | 推荐本文 |

• 作者：Digambara Patra ; ^{digpatra@hotmail.com} ; ^{dp03@aub.edu.lb} ; Christelle Barakat¹ ; Rana M. Tafech
• 关键词：Curcumin ; HSA ; Unfolding ; Refolding ; Fluorescence ; Urea
• 刊名：Colloids and Surfaces B ; Biointerfaces
• 出版年：2012
• 期刊代码：14_09277765
• 类别：ms
• 出版时间：1 June, 2012
• 卷：94
• 期：Complete
• 页码：354-361
• 文件大小：691 K

摘要

Curcumin having pharmaceutical application as anti-oxidant, anti-inflammatory and anti-carcinogenic drug necessitates studying interaction of this molecule with native, unfolded and refolded state of human serum albumin (HSA), carrier protein in the blood. We proposed a simultaneous static and dynamic fluorescence quenching mechanism operating in the complex formation between HSA and curcumin. Location of curcumin in the close proximity of tryptophan with respect to tyrosine was further evident from the observation of two fold increase in rate of depletion of SFS intensity for tryptophan with respect to tyrosine in HSA in SFS spectrum. Alteration of SFS spectral peak position, electronic absorbance, fluorescence intensity and lifetime suggested chemical denaturation by urea expectedly unfold the protein molecule in the absence and presence of curcumin. Denatured HSA had similar fluorescence peak position and lifetime to that of l-tryptophan in the polar environment. During unfolding of HSA the spectral change of tyrosine and tryptophan was resolved through synchronous fluorescence spectra at two different 螖位 in absence and presence of curcumin. It is found that curcumin remained bound to unfolded state of HSA and facilitated the process by pushing tryptophan moiety to more polar environment in the unfolded state. Dilution of the denatured protein by phosphate buffer reversibly refolded the sub-domain IIA, by also recovering fluorescence lifetime loss, but it was slow in the presence of curcumin. k_q values indicate that curcumin-HSA complex is formed in the unfolded and refolded states as observed for native state.