On the importance of π–π interactions in structural stability of phycocyanins Scientific paper

Abstract

The influences of π-π interactions in phycocyanin proteins and their environmental preferences were analyzed. The observations indicate that the majority of the aromatic residues in phycocyanin proteins are involved in π-π interactions. Phenylalanine (Phe) and tyrosine (Tyr) residues were found to be involved in π–π interactions much more frequently than tryptophan (Trp) or histidine (His). Similarly, the Phe-Phe and Tyr-Tyr π–π interacting paiThe influences of π-π interactions in phycocyanin proteins and their environmental preferences were analyzed. The observations indicate that the majority of the aromatic residues in phycocyanin proteins are involved in π-π interactions. Phenylalanine (Phe) and tyrosine (Tyr) residues were found to be involved in π–π interactions much more frequently than tryptophan (Trp) or histidine (His). Similarly, the Phe-Phe and Tyr-Tyr π–π interacting pair had the highest frequency of occurrence. In addition to π-π interactions, the arom­atic residues also form π-networks in phycocyanins. The π–π interactions are most favourable at the pair distance range of 5.5–7 Å, with a clear preference for T-shaped ring arrangements. Using ab initio calculations, we observed that most of the π-π interactions possess energy from 0 to -10 kJ mol-1. Stabil­iz­ation centres for these proteins showed that all residues found in π-π inter­actions are important in locating one or more such centres. π-π interacting resi­dues are evolutionary conserved. The results obtained from this study will be beneficial in further understanding the structural stability and eventual develop­ment of protein engineering of phycocyanins.r had the highest frequency of occurrence. In addition to π-π interactions, the arom­atic residues also form π-networks in phycocyanins. The π–π interactions are most favourable at the pair distance range of 5.5–7 Å, with a clear preference for T-shaped ring arrangements. Using ab initio calculations, we observed that most of the π-π interactions possess energy from 0 to -10 kJ mol-1. Stabil­iz­ation centres for these proteins showed that all residues found in π-π inter­actions are important in locating one or more such centres. π-π interacting resi­dues are evolutionary conserved. The results obtained from this study will be beneficial in further understanding the structural stability and eventual develop­ment of protein engineering of phycocyanins.