Enzyme-Polymer Conjugates with Photocleavable Linkers for Control Over Protein Activity.

Reversible conjugation of polymers to proteins is important for a variety of applications, for example to control protein activity. Light is often employed as an external trigger to allow for spatio and temporal control over release of a payload. In this report, we demonstrate preparation of photocleavable poly(polyethylene glycol) acrylate)-lysozyme (pPEGA-Lys) conjugates -nitrobenzyl linkages. The conjugates were made by both and in order to compare and contrast the two synthetic approaches. First, a lysine-reactive ortho-nitrobenzyl atom transfer radical polymerization (ATRP) initiator was synthesized. For the to strategy, the initiator was employed in the ATRP of PEGA, and the subsequent polymer was conjugated to the lysine residues of lysozyme. For the strategy, lysozyme was modified first with the photocleavable initiator, and the purified macroinitiator was then subjected to polymerization conditions to synthesize the protein-polymer conjugate. The polymer was cleaved from the protein UV light, and activity before and after polymer removal was evaluated, showing 83% recovery. This work provides evidence that reversing conjugation is successful for activity modulation for ortho-nitrobenzyl linked protein-polymer conjugates.