Main content area

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.