Biocatalysis of siloxane bonds

Bassindale, Alan; Brandstadt, K.F.; Lane, T.H. and Taylor, Peter (2005). Biocatalysis of siloxane bonds. In: Cheng, H.N. and Gross, Richard A. eds. Polymer Biocatalysis and Biomaterials. ACS Symposium Series (900). Oxford University Press, pp. 164–181.



The intricate siliceous architectures of diatom species have inspired our exploration of biosilicification. In order to better understand the role of various proteins in the biosilicification process, a carefully chosen model study was performed to test the ability of homologous enzymes to catalyze the formation of molecules with a single siloxane bond during the in vitro hydrolysis and condensation of alkoxysilanes. This model study is believed to be the first rigorous study to demonstrate biocatalysis at silicon. Our data suggests that homologous lipase and protease enzymes catalyze the formation of siloxane bonds under mild conditions. In particular, the active site of trypsin, a proteolytic enzyme, was determined to selectively catalyze the in vitro condensation of silanols. Conversely, the reverse reaction was not favored. Furthermore, trypsin as well as several other proteins and polypeptides promoted the hydrolysis of alkoxysilanes in a non-specific manner. Given the selectivity and mild reaction conditions of enzymes, the opportunity to strategically use biocatalysts to synthesize novel hybrid materials with structural control and spatial order is promising.

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