Interactions among proteins and hydrophobically modified polyelectrolytes

A special class of hydrophobically modified polyelectrolytes was studied wherein poly(acrylic acid) (PAA) was conjugated with Pluronic F127 NF surfactant. The Pluronic-PAA copolymer solutions form gels at low concentrations when exposed to body temperature. Such gels possess enhanced retention in topical applications. Circular dichroism spectra indicate that tertiary structures of human insulin, haemoglobin, and albumin were stabilized in solutions of Pluronic-PAA. Aggregation of insulin in gelled solutions of Pluronic-PAA was impeded as demonstrated in shaking tests. The presence of Pluronic-PAA hindered the insulin degradation by alpha -chymotrypsin by at least 7-fold. Extraction of calcium ions from trypsin by Pluronic-PAA led to the dramatic changes in the tertiary structure and total loss of enzymatic activity, suggesting that Pluronic-PAA could inhibit tryptic degradation of proteins.