it was thought earlier that inorganic materials like silica do not quite fit the bill in biological systems, since they disrupt the form and function of proteins. But a study by scientists of the Linkoping University in Sweden shows just the opposite.
The study shows that protein particles in water solution when mixed with nanoparticles of silica form a particular structure. When amino acid is added to this structure, enzymes are formed. The study will be published in the German chemistry journal Angewandte Chemie. Enzymes are biological catalysts that are essential to living cells and hence the scientists feel that this could throw new light on the mechanism of origin of life.
"We wanted to reverse the belief that inorganic substances are averse to life-system. Hence, we tried to design proteins that become functional only after encountering an inorganic surface," says Bengt-Harald Jonsson, professor of molecular biotechnology.
The team designed a peptide (a short protein) with a specific distribution of positive charges. The peptide was mixed into a solution of spherical silica particles, about nine nanometres (billionths of a metre) across. When the peptide was free in the solution it had no structure whatsoever, but when it connected with the negatively charged silica ball it assumed the form of a helix. When amino acid was added to the complex, it assumed the properties of an enzyme which catalyses reactions in living cells. This increases the prospect of the use of silica nanomaterial in medicine and biochemistry.
In another development that reinforces the utility of silica nanomaterials in enzyme activity, scientists of the Department of Energy's Pacific Northwest National Laboratory, us, found that inactive enzymes entombed in tiny honeycomb-shaped holes in silica can spring to life. The surprise discovery came after salvaging enzymes that had been in a refrigerator long past their expiry date.
To the team's surprise, enzymes that should have fizzled months before, were found active when entrapped in silica nanomaterial. The result points the way for using these enzyme traps in food processing, decontamination and any other pursuit that requires controlling catalysts and sustaining their activity.
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