Advances and trends in the design, analysis, and characterization of polymer–protein conjugates for “PEGylaided” bioprocesses

Abstract

In addition to their use as therapeutics and because of their enhanced properties, PEGylated proteins have potential application in fields such as bioprocessing. However, the use of PEGylated conjugates to improve the performance of bioprocess has not been widely explored. This limited additional industrial use of PEG-protein conjugates can be attributed to the fact that PEGylation reactions, separation of the products, and final characterization of the structure and activity of the resulting species are not trivial tasks. The development of bioprocessing operations based on PEGylated proteins relies heavily in the use of analytical tools that must sometimes be adapted from the strategies used in pharmaceutical conjugate development. For instance, to evaluate conjugate performance in bioprocessing operations, both chromatographic and non-chromatographic steps must be used to separate and quantify the resulting reaction species. Characterization of the conjugates by mass spectrometry, circular dichroism, and specific activity assays, among other adapted techniques, is then required to evaluate the feasibility of using the conjugates in any operation. Correct selection of the technical and analytical methods in each of the steps from design of the PEGylation reaction to its final engineering application will ensure success in implementing a "PEGylaided" process. In this context, the objective of this review is to describe technological and analytical trends in developing successful applications of PEGylated conjugates in bioprocesses and to describe potential fields in which these proteins can be exploited.

Preparation, characterization and molecular modeling of PEGylated human growth hormone with agonist activity

“…Various parameters were mentioned for lower biological activity of PEGylated protein, including PEG molecular weight, number of attached PEG chains and PEGylation site [36]. Moreover, masking of the amino acid sites that are critical for binding to other molecules by PEG chains may alter the affinity of hGH for its receptor [37].…”

Next Generation Delivery System for Proteins and Genes of Therapeutic Purpose: Why and How?

“…It has been shown that the reactive amino acids that often participate during this conjugation process are arginine, aspartic acid, histidine, lysine, cysteine, glutamic acid, threonine, tyrosine, and serine. Other than that, N-terminal amino group and the C-terminal carboxylic acid are also found to be involved with these reactions [105]. …”

Chemical and Genetic Modification

“…As with almost any protein therapeutic, there are issues with the manufacture, characterization, and use of PEGylated proteins [70][71][72][73][74][75], including the potential induction of anti-PEG antibodies [76], especially in the case of hyperPEGylated products that contain large numbers of conjugated PEG molecules [77][78]. Many proteins used as therapeutics display some propensity for immunogenicity [79][80][81][82][83][84].…”