Good news! Human ingenuity will take care of the plastic waste problem!
"For the first time, scientists have engineered an enzyme that can break stubborn man-made bonds between silicon and carbon that exist in widely used chemicals known as siloxanes, or silicones. The discovery is a first step toward rendering the chemicals, which can linger in the environment, biodegradable. ..."
From the editor's summary and abstract:
"Editor’s summary
Methylsiloxanes are organosilicon compounds produced by humans for use in a wide range of consumer products. Because they are not naturally found in nature, they are not readily degraded by organisms and some also have the potential to bioaccumulate. Sarai et al. identified a cytochrome P450 enzyme that can perform a hydroxylation on the methyl groups of linear methylsiloxanes. They then expanded this activity using directed evolution, creating variants that were more efficient and also functioned on cyclic methylsiloxanes. Mechanistic experiments suggested that a second oxidation and an enzyme-facilitated rearrangement can lead to cleavage of the carbon–silicon bond and release of formaldehyde. ...
Abstract
Volatile methylsiloxanes (VMS) are man-made, nonbiodegradable chemicals produced at a megaton-per-year scale, which leads to concern over their potential for environmental persistence, long-range transport, and bioaccumulation. We used directed evolution to engineer a variant of bacterial cytochrome P450BM3 to break silicon-carbon bonds in linear and cyclic VMS. To accomplish silicon-carbon bond cleavage, the enzyme catalyzes two tandem oxidations of a siloxane methyl group, which is followed by putative [1,2]-Brook rearrangement and hydrolysis. Discovery of this so-called siloxane oxidase opens possibilities for the eventual biodegradation of VMS."
Directed evolution of enzymatic silicon-carbon bond cleavage in siloxanes (no public access)
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