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Title of article :
Folding and stability studies on C-PE and its natural N-terminal truncant
Author/Authors :
Anwer، نويسنده , , Khalid and Parmar، نويسنده , , Asha and Rahman، نويسنده , , Safikur and Kaushal، نويسنده , , Avani and Madamwar، نويسنده , , Datta and Islam، نويسنده , , Asimul and Hassan، نويسنده , , Md. Imtaiyaz and Ahmad، نويسنده , , Faizan، نويسنده ,
Issue Information :
روزنامه با شماره پیاپی سال 2014
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Abstract :
The conformational and functional state of biliproteins can be determined by optical properties of the covalently linked chromophores. α-Subunit of most of the phycoerythrin contains 164 residues. Recently determined crystal structure of the naturally truncated form of α-subunit of cyanobacterial phycoerythrin (Tr-αC-PE) lacks 31 N-terminal residues present in its full length form (FL-αC-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-αC-PE and Tr-αC-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 Δ G D ∘ , the value of Gibbs free energy change on denaturation (ΔGD) in the absence of GdmCl. The main conclusions of the this study are: (i) GdmCl-induced denaturation (native state ↔ denatured state) of FL-αC-PE and Tr-αC-PE is reversible and follows a two-state mechanism, (ii) FL-αC-PE is 1.4 kcal mol−1 more stable than Tr-αC-PE, (iii) truncation of 31-residue long fragment that contains two α-helices, does not alter the 3-D structure of the remaining protein polypeptide chain, protein–chromophore interaction, and (iv) amino acid sequence of Tr-αC-PE determines the functional structure of the phycoerythrin.
Keywords :
Biliproteins , chromophore , Protein denaturation , Folding and stability , C-phycoerythrin
Journal title :
Archives of Biochemistry and Biophysics
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