Poly(2‐oxazoline)s terminated with 2,2′‐imino diacetic acid form noncovalent polymer–enzyme conjugates that are highly active in organic solvents

Abstract

A great limitation for the usability of free enzymes in organic solvents is their insolubility in these media. Some surfactants are capable of solubilizing enzymes in such media, but they are hard to remove. Covalent modification of enzymes with polymers has led to polymer-enzyme conjugates (PECs) that are soluble in organic solvents, but the process is quite elaborate. Poly(2-oxazoline)s (POx) with the end group 2,2′-imino diacetic acid were shown to form reversible, nano-sized noncovalent aggregates with enzymes. These PECs give clear solutions in organic solvents. The enzymes lysozyme, horseradish peroxidase (HRP), laccase, α-chymotrypsin (CT), catalase, and alcohol dehydrogenase could be solubilized in chloroform and toluene at concentrations of up to 2 mg protein/ml. Laccase, HRP, and CT were shown to survive the transfer into the organic medium and back to water in their active form. The distribution coefficient of the proteins between water and the organic solvent was shown to be dependent on the nature of the POx backbone. All three biocatalysts exhibit greatly enhanced activity in the respective organic solvent. K E Y W O R D Sbiocatalysis, enzyme, noncovalent polymer-enzyme conjugate, organic solvent, poly(2-oxazoline)

Poly(2‐oxazoline)s with a 2,2′‐Iminodiacetate End Group Inhibit and Stabilize Laccase

“…The interaction of these POx-IDA species with proteins is so strong that they form noncovalent, organosoluble conjugates with the latter. [19] Herein, we show how POx-IDAs inhibitt he enzyme laccase and even stabilizethis relatively fragile enzyme.…”

“…This is remarkable because IDA is not an inhibitor of HRP. The interaction of these POx‐IDA species with proteins is so strong that they form noncovalent, organosoluble conjugates with the latter …”

Process Intensification as Game Changer in Enzyme Catalysis

“…Hydroxynitrile lyases (HNLs) are preferentially used under non-aqueous conditions to suppress the non-catalysed addition of HCN (or its anion) to the carbonyl group yielding racemic product [Scheme 1B, (Paravidino et al, 2010;Scholz et al, 2012)]. In case of ADH-catalysed redox reactions, non-aqueous media circumvent the diffusion of the nicotinamide cofactor and thereby further protect it from aqueous degradation [Scheme 1C, (Kara et al, 2014;Jakoblinnert et al, 2011;Hibino and Ohtake, 2013;Erdmann et al, 2014;Hijazi et al, 2019)]. More recently, also reductive aminations [Scheme 1D, (Böhmer, 2020)] and oxyfunctionalisations in non-aqueous media have been reported [Scheme 1E, (Rauch et al, 2019)].…”

Hot melt extrusion: An emerging manufacturing method for slow and sustained protein delivery

“…In brief, the “graft‐to” strategy is coupling a pre‐polymerized functional polymer to the surface of the protein. Polynorbornene (Isarov et al, 2016), poly(HPMA) (Tao et al, 2009), and poly(2‐oxazoline)s (Hijazi et al, 2019) were successfully attached to proteins with this “graft‐to” approach, among many others. In contrast, “graft‐from” is a strategy that in situ polymerization from a modified/or non‐modified protein surface (Figure 6b).…”