Synthesis of homopolypeptides by aminolysis mediated by proteases encapsulated in silica nanospheres.

We report the encapsulation of three different proteases in bioinspired silica. Silica particles were formed under mild reaction conditions using cationic amine-rich ethyleneamines as initiators, which resulted in aggregations of nanoscale spheres. Following encapsulation, the proteases were characterized for their hydrolytic and aminolytic activities. The encapsulation resulted in an increase in the thermal stability of the proteases for both hydrolysis and aminolysis reactions. The enhanced thermal stability of the encapsulated proteases increased the production of poly-L-leucine by aminolysis. Furthermore, the encapsulation of papain resulted in an increase in the production of poly-L-alanine and poly-L-valine at 50 °C.