The enzymatic reactions were stopped by adding equal volumes of methanol with 0.5 % (v/v) formic acid. After centrifugation (16,000 xg, 10 min), the supernatants were separated in a Nucleodur C18 analytical EC standard column (5 µm, 4 × 125 mm, Macherey-Nagel) on a 1260 Infinity II (Agilent) HPLC. To detect TPA, the mobile phase running at 1 mL min -1 consisted of buffer A (0.1% formic acid in distilled water), buffer B (distilled water), and buffer C (acetonitrile). The infusion rate of buffer A was kept constant at 20%; those of B and C was altered (5 min, 72% and 8%; 13 min, 50% and 30%; 17 min, 30% and 50%; 18 min, 10% and 70%). The monomers were detected at λ=250 nm and quantified using calibration curves. To detect the release of 6-hydroxycaproic acid, the mobile phase mixtures of buffer A (Milli-Q water) and buffer B (acetonitrile) were used at a flow rate of 1 mL min -1 . Buffer A was kept at 100% for 5 min. The mobile phase was changed gradually to 100% buffer B until 10 min. Afterwards it was changed back to 100% buffer A until 15 min. 6-hydroxyhexanoic acid was detected at 190 nm and 220 nm by comparison with authentic samples and quantified by calibration curves.