Sobia Zaidi1, Shah Ubaid-ullah1, Md. Anzarul Haque1, Md. Imtaiyaz Hassan1, JK Batra2, Faizan Ahmad1
1Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi 110025, India.
2Immunochemistry Lab, National Institute of Immunology, Aruna Asaf Ali Road, New Delhi 110067, India.
Cytochrome-c (cyt-c) is an intensively studied protein because of its central role in the electron transfer in living organisms. The availability of large number of sequences and high-resolution crystallographic data of cyt-c, made this protein as a model system to study the evolution of protein sequence and structure. Sequence analysis suggests that yeast cyt-c (y-cyt-c) has five extra N-terminal residues in comparison to the mammalian cytochromes c. Structure analysis suggests that these five N-terminal residues are forming numerous van der Waals interactions to the protein atoms. In order to establish the role of these extra N-terminal residues in the conformation and stability y-cyt-c, we sequentially deleted all five N-terminal residues. All five deletants and wild type protein were expressed in bacterial cell, BL21. We measured several spectroscopic properties including, absorption spectra, Near UV, far UV, Soret CD spectra, and fluorescence of different variants of y-cyt-c. All spectroscopic observations suggest that a successive deletion of each N-terminal residue led to minor change in the structural features of y-cyt-c. Read more…