Purification and partial characterization of polygalacturonase from Streptomyces lydicus.

Abstract Polygalacturonase produced by Streptomyces lydicus was purified to homogeneity by ultrafiltration and a combination of ion exchange and gel filtration chromatographic procedures. The purified enzyme was an exo-polygalacturonase with a molecular weight of 43 kDa. It was optimally active at 50 °C and pH 6.0. The enzyme was stable from pH 4.0 to 7.0 and at or below 45 °C for 90 min. K m value for polygalacturonic acid was 1.63 mg/mL and the corresponding V max was 677.8 μM min −1 mg −1 . The inhibition constant ( K i ) for gluconic acid d -lactone was 20.75 mM. Purified enzyme had been inhibited by N-bromosuccinimide, while l -tryptophan could induce enzyme activity, indicating the involvement of tryptophan at the active site.