Improving enzymatic polyurethane hydrolysis by tuning enzyme sorption

• Published in: Polymer degradation and stability Vol. 132; pp. 69 - 77
• Main Authors: Gamerith, Caroline, Herrero Acero, Enrique, Pellis, Alessandro, Ortner, Andreas, Vielnascher, Robert, Luschnig, Daniel, Zartl, Barbara, Haernvall, Karolina, Zitzenbacher, Sabine, Strohmeier, Gernot, Hoff, Oskar, Steinkellner, Georg, Gruber, Karl, Ribitsch, Doris, Guebitz, Georg M.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.10.2016
• Subjects: Enzymatic degradation; Functionalization; Polyamidase; Polyurethane; Polyurethane model substrate; Polyamidase; Enzymatic degradation; Functionalization; Polyurethane; Polyurethane model substrate
• ISSN: 0141-3910; 1873-2321
• DOI: 10.1016/j.polymdegradstab.2016.02.025

In this study we investigated the ability of amidases to hydrolyse polyurethane polyester co-polymers. In order to improve enzyme adsorption, a polyamidase from Nocardia farcinica (PA) was fused to a polymer binding module from a polyhydroxyalkanoate depolymerase from Alcaligenes faecalis (PA_PBM). The activity of these enzymes and of various commercially available amidases on a synthesized soluble model substrate was compared. The recombinant native PA showed the highest activity of 10.5 U/mg followed by PA_PBM with an activity of 1.13 U/mg. Both enzymes were able to cleave the urethane bond in polyurethane-polyesters with different degree of crystallinity as shown by FTIR. According to LC-TOF analysis the monomer 4,4′-diaminodiphenylmethane (MDA) and the oligomers 4-hydroxybutyl (3-(3-aminobenzyl)phenyl)carbamate [B], bis(4-hydroxybutyl) (methylenebis(3,1-phenylene))dicarbamate [C] and 4-(((3-(3-(((4-hydroxybutoxy)carbonyl)amino)benzyl)phenyl)carbamoyl)oxy)butyl (4-hydroxybutyl) adipate [D] were released. The polymer with a higher content of the rigid segment, MDA, was hydrolysed to a lower extent. Interestingly, despite the lower activity on the soluble model substrate, the PA_PBM fusion enzyme was up to 4 times more active on the polymer when compared with the native enzyme, confirming the relevance of enzyme adsorption for efficient hydrolysis. Scheme of enzymatic PU hydrolysis by PA or PA_PBM leading to the release of 4,4′-diaminodiphenylmethane. [Display omitted]