Sabab Hasan Khan, Md. Imtaiyaz Hassan, Faizan Ahmad
Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi 110025, India.
Cytochrome c (Cyt-c) is an electron carrier protein belongs to cytochrome c family. Cyt-c is involved in many processes like electron transfer in respiratory chains, apoptosis, oxidation of cardiolipin etc. It is a 104 residue long polypeptide chain binds 1 heme group per subunit, believed that heme is involved in helical structure formation and protein folding. There are more than 300 sequences of cyts-c have been reported from various sources, and showed many evolutionary conserved residues. It is evident from structure and function studies of cyt-c that only few residues are important for protein folding and stability, out of 104 amino-acids. Apart from heme-binding, residues such as Cys13, Cys14, His18, there are four positions in cyts-c, which are conserved in all subfamilies. These positions are Gly/Ala6, Phe/Tyr10, Leu/Val/Phe94 and Tyr/Trp/Phe97. Crystal structure analysis suggests that these residues form many significantly strong contacts and hence these are quite important for the protein folding. It is noteworthy that there are 23 interatomic contacts between the N and C-terminal helices, are offered by only these conserved residues, which substantially contributing to the stability of the folded protein. These residues are also termed as key residues. Here we have analyzed the role of key residues in the protein folding and stability using in silico approach. Read More …