Aggregation Behavior of Giant Amphiphiles Prepared by Cofactor Reconstitution

Abstract

We report on biohybrid surfactants, termed "giant amphiphiles", in which a protein or an enzyme acts as the polar head group and a synthetic polymer as the apolar tail. It is demonstrated that the modification of horseradish peroxidase (HRP) and myoglobin (Mb) with an apolar polymer chain through the cofactor reconstitution method yields giant amphiphiles that form spherical aggregates (vesicles) in aqueous solution. Both HRP and Mb retain their original functionality when modified with a single polystyrene chain, but reconstitution has an effect on their activities. In the case of HRP the enzymatic activity decreases and for Mb the stability of the dioxygen myoglobin (oxy-Mb) complex is reduced, which is probably the result of a disturbed binding of the heme in the apo-protein or a reduced access of the substrate to the active site of the enzyme or protein.

Self‐Assembled Block Copolymer Aggregates: From Micelles to Vesicles and their Biological Applications

“…[112] Biohybrid 'giant-amphiphiles' consisting of a synthetic polymer chain linked to a functional protein can form vesicles that retain the enzymatic activity of the protein. [113,114] Vesicles with biologically relevant coronal hydrophilic moieties have also been developed from both oligonucleotide dCMP sequences [115] and polysaccharides. [116][117][118] Biocompatible Copolymer Vesicles and the Delivery of Actives…”

Functionalization of Block Copolymer Vesicle Surfaces

“…Nolte and co-workers introduced a route to giant amphiphiles by cofactor reconstitution (Figure 13(a)). A synthetic polymer, PS-b-PEG, was first functionalized with a heme cofactor, protoporphyrin IX, and subsequently reconstituted with an apoprotein, myoglobin (Mb) or HRP [94,95]. The PS-b-PEG precursor formed small spherical micelles in water; the solution was prepared by injection of the polymer in THF into water.…”

“…Whether the membrane has a mono-or a bilayered structure, and whether the PEG and HRP are segregated or mixed in the corona, is not yet known. The enzyme-polymer hybrid vesicles were further investigated according to their enzymatic activity [95,96]. The enzymatic activity decreased for HRP and the stability of the oxy complex was reduced for Mb.…”

Protein–Polymer Hybrid Amphiphiles

“…In addition to HRP, the oxygen-binding protein myoglobin (Mb) could also be employed to construct noncovalently linked biohybrid amphiphiles, following the same reconstitution approach. [11] Another approach to prepare noncovalently linked protein-polymer amphiphiles, is via the biotin-streptavidin couple although it should be noted here that the affinity between biotin and streptavidin is so high (K a % 10 15 M…”