Khalid Anwer1, Safikur Rahman1, Asha Parmar2, Avani Kaushal2, Datta Madamwar2, Faizan Ahmad1, Md Imtaiyaz Hassan1
1Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia (Central University), Jamia Nagar, New Delhi 110 025, India.
2BRD School of Biosciences, Sardar Patel University, Vallabh Vidyanagar, Gujarat 388 120, India.


The conformational changes during folding/unfolding process of biliproteins (BPs) are of great importance because of its potential role in energy transfer in photosynthesis. The phycoerythrin of Phormidium tenue is hexameric protein (αβ) 6, and its alpha-subunit consists of 164 amino acids (19kDa). The multimeric protein assembly forms stable arrangement however, undergoes degradation in the starved condition and releasing a truncated α-subunit of 133 amino acid residues only (devoid of 31 N-terminal residues). Recently, this naturally truncated form of alpha-subunit discovered and its crystal structure was determined successfully. Here we performed the denaturation studies using GdmCl, urea and weak salt like LiCl, using UV-visible absorbance, CD and fluorescence spectroscopy on both wild type and truncated C-PE. These denaturation studies suggest that a minor difference in the ∆GD° (~1.0 kcal mol -1 ) and Cm (~0.25 in M GdmCl) of full length and truncated proteins. Furthermore, GdmCl-induced denaturation is reversible in both the cases. The transition curves of different probes are precisely overlapping on f d plot, suggests that GdmCl-induced denaturation is a two-step process in truncated as well as in full length C-PE. The difference in the ∆GD° value of both the proteins is quite less, indicates that both proteins are approximately equally stable and the deletion of does not alters its function. Read more…

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