Interactions among proteins and hydrophobically modified polyelectrolytes

A special class of hydrophobically modified polyelectrolytes was studied wh erein poly(acrylic acid) (PAA) was conjugated with Pluronic F127 NF surfact ant. The Pluronic-PAA copolymer solutions form gels at low concentrations w hen exposed to body temperature. Such gels possess enhanced retention in to pical applications. Circular dichroism spectra indicate that tertiary struc tures of human insulin, haemoglobin, and albumin were stabilized in solutio ns 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-f old. Extraction of calcium ions from trypsin by Pluronic-PAA led to the dra matic changes in the tertiary structure and total loss of enzymatic activit y, suggesting that Pluronic-PAA could inhibit tryptic degradation of protei ns.