Hu_2016_Polym.Degrad.Stab_134_211

A gene encoding cutinase from Fusarium solani was cloned and overexpressed in Pichia pastoris. The recombinant cutinase with a molecular weight of 24 kDa was then purified to homogeneity. The enzyme presents degradation capacity for poly(butylene succinate) (PBS) and exhibits the optimum pH and temperature of 8.0 and 50 C, respectively. Enzyme activity is enhanced by K+ and Na+ and inhibited by Zn2+,Fe2+ ,Mn2+, and Co2+. The inhibitions of different chemicals on recombinant enzyme activity were examined. EDTA and b-mercaptoethanol exert significant inhibitory effect. The degradation of PBS films in the presence of the recombinant enzyme was further studied. Results showed that enzymatic degradation is a rapid process, and the PBS fi lms were degraded completely after approximately 6 h. The characteristics of PBS films after degradation were analyzed. With the extension of degradation time, the surfaces of PBS films became rougher and holes appeared with a gradually increasing trend. Differential scanning calorimetry and scanning electron microscopy analyses revealed that both amorphous and crystalline regions of PBS were degraded by the recombinant enzyme. Wide-angle X-ray diffractometer also indicated the crystallinity of PBS has a gradual downward trend with the extension of degradation time. Gel permeation chromatography showed the molecular weight of PBS has no obvious change before and after degradation.