Identification of Bilirubin Binding Site in Type I

Authors: Nagarajan Usharani Gladstone Christopher Jayakumar Swarna V Kanth Jonnalagadda Raghava Rao Bangaru Chandrasekaran Balachandran Unni Nair

Publish Date: 2013/07/18

Volume: 19, Issue: 4, Pages: 357-364

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Abstract

The interaction of bilirubin with collagen in the significance of jaundice incidence have been previously reported and investigated The novel peptide sequences containing bilirubin binding domain was identified and located to develop a basis for further studies investigating the interactions of collagen with bilirubin in the present study In this study an intricate interaction between bilirubin and collagen was characterized and their binding domain has been established using ingel digestion and LC–MS/MS analysis based on the collagen sequencing and peptide mass fingerprinting The biotinylated bilirubin derivatives bind to α1I chain but not to α2I chains which clearly designates that bilirubin shows greater affinity to α1 chains of collagen The intact proteins collected after analyzing the resulting complex mixture of peptides was used for peptide mapping Using the electrospray method among the other peptide sequence information obtained the molecular weight of collagen alpha2I chain was obtained by locating a 130 kDa weight peptide sequences with greater pi value 914 with 1364 amino acid residues and collagen alpha1I chain with 1463 amino acid residues with 1389 kDa molecular weight This information leads to locate the exact sequence of these helices focussing on the domain identification The total charge of the peptide domain sequences infers that the bilirubin participates in the electrostatic mode of interaction with collagen peptide Moreover other modes of interactions such as hydrogen bonding covalent interactions and hydrophobic interactions are possible

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