Convenient Approach to Polypeptide Copolymers Derived from Native Proteins

Abstract

A convenient approach for the synthesis of narrowly dispersed polypeptide copolymers of defined compositions is presented. The controlled denaturation of the proteins serum albumin and lysozyme followed by an in situ stabilization with polyethylene(oxide) chains yields polypeptide side chain copolymers of precisely defined backbone lengths as well as the presence of secondary structure elements. Supramolecular architectures are formed in solution because of the presence of hydrophobic and hydrophilic amino acids along the polypeptide main chain. Polypeptide copolymers reported herein reveal excellent solubility and stability in aqueous media and no significant cytotoxicity at relevant concentrations, and they can be degraded via proteolysis, which is very attractive for biomedical applications. This "semi-synthetic chemistry" approach is based on a novel and convenient concept for producing synthetic polypeptides from native protein resources, which complements traditional polypeptide synthesis and expression approaches and offers great opportunities for the preparation of diverse polypeptides with unique architectures.

Precision Biopolymers from Protein Precursors for Biomedical Applications

“…A major challenge for the preparation of biopolymers from proteins is the unfolding and denaturation, which often leads to the destabilization and precipitation of the resulting polypeptide 17. A “denaturation–PEGylation” approach has been developed on the basis of a semi‐synthetic strategy yielding water‐soluble polypeptide copolymers (PcPs) bearing polyethylene oxide (PEO) side chains with narrow size distributions, defined contour lengths and multiple functionalities that adopt brush‐like architectures (Figure 2).…”

“…A “denaturation–PEGylation” approach has been developed on the basis of a semi‐synthetic strategy yielding water‐soluble polypeptide copolymers (PcPs) bearing polyethylene oxide (PEO) side chains with narrow size distributions, defined contour lengths and multiple functionalities that adopt brush‐like architectures (Figure 2). 17 Different protein precursors have been selected to prove the general applicability of this approach. Lysozyme from hen's egg white (LY), bovine (BSA), and human serum albumin (HSA) represent low‐ and high‐molecular‐weight proteins, respectively, that facilitate the preparation of copolymers with long and short contour lengths from protein precursors that are commercially available for reasonable prices and larger quantities (grams).…”

“… Preparation of brush‐like copolymers based on albumin and lysozyme protein precursors 17. The high‐molecular‐weight protein–polymer dimer BSA‐PEO(3400)‐BSA represents a macromolecular precursor of narrow size dispersity that allows access to polypeptide–PEO triblock copolymers of high structural definition 18…”

“…In case of the albumin precursor proteins, about 27 out of 35 cysteine groups could be functionalized reproducibly with the PEO linker. This result is attributed to the polypeptide sequence of serum albumin in which eight cysteine residues are located directly next to each other and therefore, two adjacent thiols cannot react for steric reasons 17. However, these unreacted thiol groups can be modified with the smaller reagent N‐(2‐aminoethyl)maleimide and this “capping step” further increases the shelf lives of the albumin copolymers (Figure 2).…”

Polymer-Albumin Conjugate for the Facilitated Delivery of Macromolecular Platinum Drugs

“…Careful denaturation of the albumin led to unfolding and the formation of hydrophobic pockets that are ideal for drug encapsulation. [ 10 ] Chemical attachment has also been used to directly link drugs such as platinum drugs to albumin, although the resulting carrier is not a nanoparticle in the traditional sense considering that the size of albumin is below 6 nm. [ 11 ] The interest in albumin as drug carrier stems from the high accumulation of the protein in tumors due to the increased metabolization in the carcinoma site, which is enhanced by the receptor glycoprotein gp60 and subsequent bind ing to Secreted Protein, Acidic and Richin Cysteine in the tumor extracellular matrix.…”