An active recombinant cocoonase from the silkworm Bombyx mori: bleaching, degumming and sericin degrading activities

作者：Unajak Sasimanas; Aroonluke Suradet; Promboon Amornrat^*

来源：Journal of the Science of Food and Agriculture, 2015, 95(6): 1179-1189.

DOI：10.1002/jsfa.6806

• Bombyx mori
• cocoonase
• yeast expression system
• bleaching
• degumming
• sericin degrading

BACKGROUNDCocoonase is a serine protease produced by silk moths and used for softening the cocoons so that they can escape. Degumming is one of the important steps in silk processing. This research aimed to produce an active recombinant Bombyx mori cocoonase (BmCoc) for the silk degumming process.
RESULTSA recombinant BmCoc was successfully expressed in a Pichia pastoris system. The purified enzyme showed specific activity of 227 U mg(-1) protein, 2.4-fold purification, 95% yield and a molecular weight of 26kDa. The enzyme exhibited optimal temperature at 40 degrees C and optimal pH at 8, and showed thermal stability at 25-45 degrees C and pH stability at 5-9. The recombinant enzyme exhibited sericin degumming ability and color bleaching characteristics, and did not affect the fibroin fiber. The enzyme also degraded sericin substrate with a product size about 30-70kDa.
CONCLUSIONIn this study, we successfully produced the active recombinant BmCoc in P. pastoris with promising functions for the Thai silk degumming process, which includes degumming, sericin degrading and color bleaching activities. Our data clearly indicated that the recombinant enzyme had proteolytic activity on sericin but not on fibroin proteins. The recombinant BmCoc has proven to be suitable for numerous applications in the silk industry.

• 出版日期2015-4