Study of Residue Closeness Centrality and its Significance in Predicting Cdr Regions in Antibody Light Chains

According to facts, residues with high closeness centrality value play a vital role in transmitting information to other amino acid residues in the protein structure, thus fulfill essential roles in the network's communication. [...]concluding from the study conducted by Fujihashi in 2006, it was seen that active site residues found in clefts or cavities on enzymes were observed to have high closeness centrality value. To identify functionally important residues in Human Antibody Light Chain Variable Domain (HALCVD) and to determine their role in antigen-antibody interaction, a dataset of 28 nonredundant antibody sequences was created. Since the CDR regions are incorporated only in the variable domains of both the chains of the antibody and because our study was localized to light chains only, we retrieved the sequences of the variable domains of the light chains of all the human antibodies under study. Conserved residues were seen localized to the Fr regions which form the ß sheet to form a scaffold that holds the CDR residues in place for effective interaction with its corresponding epitope on the antigen. Since these centrally conserved residues of the Fr region are a part of the variable domain, it is safe to assume that their function is also related to the formation of the antigen-antibody complex. Since these centrally conserved residues belong to the Fr regions that form the ß sheet scaffold to hold the CDR regions in place, they are embedded in the paratopic cleft and exposed like CDR residues in the form of consecutive bulges(15).