Polyamide (PA)

Polyamide (CHEBI:61445) is a polymer (thermoplast) of repeating units of aliphatic, semi-aromatic or aromatic molecules linked via amide bonds. The best-known synthetic polymers are Nylon and Kevlar. Polyamides are mainly used in textiles, automotive applications, carpets and sportswear. Remarkably, proteins as well as natural silk are polyamides per se. Based on this, it should be expected that nature has evolved enzymes that act on these non-native polymers. However, to date, there is no microorganism known that is able to fully degrade the intact high-molecular-weight polymer. Notably, some fungal peroxygenases/laccases have been proposed to be acting on the larger polymer. But today no enzyme sequence has been linked with those reports. However, several studies show that bacteria act on either linear or cyclic nylon oligomers with rather short chain lengths.

Currently known and biochemically characterized active PA oligomer hydrolases are listed below. Model enzymes are: NylA is a 6-aminohexanoate cyclic dimer hydrolase (amidase) (EI); NlyB is a linear 6-aminohexanoate dimer hydrolase (EII).; NylC hydrolyzes linear trimer, tetramer, and pentamer of 6-aminohexanoate by an endo-type reaction (EII). Predicted and not characterized enzymes are not included. For PDB entries only one lead structure is included. In case you are aware of PA-active (polymer or oligomer) biochemically characterized enzymes that are not listed below, please contact the PAZy team.

Cite: Buchholz, P.C.F., Feuerriegel, G., Zhang, H., Perez-Garcia, P., Nover, L.-L., Chow, J., Streit, W.R. and Pleiss, J (2022);
Plastics degradation by hydrolytic enzymes: The Plastics-Active Enzymes Database - PAZy
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