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Poly(N-isopropylacrylamide-co-tris-nitrilotriacetic acid acrylamide) for a Combined Study of Molecular Recognition and Spatial Constraints in Protein Binding and Interactions
- Liu, Juan, Spulber, Mariana, Wu, Dalin, Talom, Renee M., Palivan, Cornelia G., Meier, Wolfgang
- Journal of the American Chemical Society 2014 v.136 no.36 pp. 12607-12614
- acrylamides, binding capacity, binding sites, collagenase, copper, histidine, models, molecular weight, polymers, protein binding, topology, yellow fluorescent protein
- Many biological processes require precise regulation and synergy of proteins, and consequently involve molecular recognition and spatial constraints between biomolecules. Here, a library of poly(N-isopropylacrylamide-co-tris-nitrilotriacetic acid acrylamide) (PNTs) has been synthesized and complexed with Cu²⁺ in order to serve as models for investigation of the combined effects of molecular recognition and spatial constraints in biomolecular interactions. The average distance between Cu²⁺–trisNTA binding sites in PNTs polymers was varied from 4.3 to 31.5 nm by adjusting their trisNTA contents. His tag (His₆), His-tagged enhanced yellow fluorescent protein (His₆-eYFP), and His₆-tagged collagenase G (His₆-ColG), with sizes ranging from 1 to 11 nm, were used as models to assess whether the binding ability is influenced by a cooperative topology based on molecular recognition interactions with Cu²⁺–trisNTA binding sites, and spatial constraints created by decreasing average distance between trisNTAs. His-tagged molecules bound to all PNTs polymers due to their molecular recognition interaction involving histidines and Cu²⁺–trisNTA pockets, but with a binding ability that was highly modulated by the average distance between the trisNTA binding sites. Small molecular mass molecules (His₆) exhibit a high binding ability to all PNTs polymers, whereas his-tagged proteins bind to PNTs efficiently only when the average distance between trisNTA binding sites is larger than the protein dimensions.