Folding and stability studies on C-PE and its natural N-terminal truncant

详细信息    查看全文

• 作者：Khalid Anwer^a ; Asha Parmar^b ; Safikur Rahman^a ; Avani Kaushal^b ; Datta Madamwar^b ; Asimul Islam^a ; Md. Imtaiyaz Hassan^a ; ^{mihassan@jmi.ac.in" class="auth_mail} ; Faizan Ahmad^a
• 关键词：Biliproteins ; C-phycoerythrin ; Chromophore ; Protein denaturation ; Folding and stability
• 刊名：Archives of Biochemistry and Biophysics
• 出版年：1 March, 2014
• 年：2014
• 卷：545
• 期：Complete
• 页码：9-21
• 全文大小：3104 K

文摘

The conformational and functional state of biliproteins can be determined by optical properties of the covalently linked chromophores. 伪-Subunit of most of the phycoerythrin contains 164 residues. Recently determined crystal structure of the naturally truncated form of 伪-subunit of cyanobacterial phycoerythrin (Tr-伪C-PE) lacks 31 N-terminal residues present in its full length form (FL-伪C-PE). This provides an opportunity to investigate the structure-function relationship between these two natural forms. We measured guanidinium chloride (GdmCl)-induced denaturation curves of FL-伪C-PE and Tr-伪C-PE proteins, followed by observing changes in absorbance at 565 nm, fluorescence at 350 and 573 nm, and circular dichroism at 222 nm. The denaturation curve of each protein was analyzed for , the value of Gibbs free energy change on denaturation (螖G_D) in the absence of GdmCl. The main conclusions of the this study are: (i) GdmCl-induced denaturation (native state 鈫?#xA0;denatured state) of FL-伪C-PE and Tr-伪C-PE is reversible and follows a two-state mechanism, (ii) FL-伪C-PE is 1.4 kcal mol^鈭? more stable than Tr-伪C-PE, (iii) truncation of 31-residue long fragment that contains two 伪-helices, does not alter the 3-D structure of the remaining protein polypeptide chain, protein-chromophore interaction, and (iv) amino acid sequence of Tr-伪C-PE determines the functional structure of the phycoerythrin.