A Novel Aryl Acylamidase From Nocardia farcinica Hydrolyses Polyamide

An alkali stable polyamidase was isolated from a new strain of Nocardia farcinica . The enzyme consists of four subunits with a total molecular weight of 190 kDa. The polyamidase cleaved amide and ester bonds of water inso- luble model substrates like adipic acid bishexylamide and bis(benzoyloxyethyl)terephthalate and hydrolyzed different soluble amides to the corresponding acid. Treatment of polyamide 6 with this amidase led to an increased hydro- philicity based on rising height and tensiometry measure- ments and evidence of surface hydrolysis of polyamide 6 is shown. In addition to amidase activity, the enzyme showed activity on p-nitrophenylbutyrate. On hexanoamide the amidase exhibited a Km value of 5.5 mM compared to 0.07 mM for p-nitroacetanilide. The polyamidase belongs to the amidase signature family and is closely related to aryl acylamidases from different strains/species of Nocardia and to the 6-aminohexanoate-cyclic dimer hydrolase (EI) from Arthrobacter sp. KI72.