[Purification of monoamine oxidase B from porcine liver]

Monoamine oxidase B (MAOB) was purified from porcine liver by solubilization with lysis buffer containing 1% Triton X-100, precipitation with 20%-50% ammonium sulfate, isolation with hydrophobic chromatography and anion exchange chromatography. The purification fold was 18.2. The specific activity was 135 U/mg. The purified enzyme appeared homogeneous by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and it had a relative molecular mass of about 60,000. The identification of the enzyme was confirmed by high performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS). As MAOB is a membrane enzyme, a key step to the successful purification was the use of Phenyl-Sepharose CL-4B with phenyl density of 75.7 micromol/mL. The results showed that this approach could effectively isolate MAOB from porcine liver to yield an enzyme with high purity and specific activity.