title: Replica exchange Monte Carlo simulation of human serum albumin-catechin complexes.
abstract: Replica exchange Monte Carlo simulation equipped with an orientation-enhanced hydrophobic interaction was utilized to study the impacts of molar ratio and ionic strength on the complex formation of human serum albumin (HSA) and catechin. Only a small amount of catechins was found to act as bridges in the formation of HSA-catechin complexes. Selective binding behavior was observed at low catechin to HSA molar ratio (R). Increase of catechin amount can suppress HSA self-aggregation and diminish the selectivity of protein binding sites. Strong saturation binding with short-range interactions was found to level off at around 4.6 catechins per HSA on average, while this number slowly increased with R when long-range interactions were taken into account. Meanwhile, among the three rings of catechin, the 3,4-dihydroxyphenyl (B-ring) shows the strongest preference to bind HSA. Neither the aggregation nor the binding sites of the HSA-catechin complex was sensitive to ionic strength, suggesting that the electrostatic interaction is not a dominant force in such complexes. These results provide a further molecular level understanding of protein-polyphenol binding, and the strategy employed in this work shows a way to bridge phase behaviors at macroscale and the distribution of binding sites at residue level.
authors.affiliation: Laboratory of Advanced Power Sources and ‡State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry (CIAC) , Changchun 130022, P. R. China.
authors.forename: Yunqi
authors.initials: Y
authors.lastname: Li
authors.forename: Lijia
authors.initials: L
authors.lastname: An
authors.forename: Qingrong
authors.initials: Q
authors.lastname: Huang
mesh_terms: D000465:Algorithms; D002392:Catechin / Q000737:chemistry*; D003198:Computer Simulation; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D007477:Ions / Q000737:chemistry; D008958:Models, Molecular; D009010:Monte Carlo Method; D011485:Protein Binding; D012709:Serum Albumin / Q000737:chemistry*; D055672:Static Electricity
chemical_list: D007477:Ions; D012709:Serum Albumin; D002392:Catechin