Silaffin

A silaffin is a modified peptide associated with the silica-containing cell wall of a diatom. Silaffins help explain how an organism can promote mineral formation under conditions compatible with a living biological cell.

In a 1999 experiment, purified silaffins extracted from diatom walls rapidly generated networks of silica nanospheres when added to a silicic-acid solution. Chemical analysis identified modified lysine residues, and the modifications affected silica-precipitating activity.^[ref] The result demonstrates direct promotion of mineral deposition by an organic component. It does not alone explain the full patterned geometry of a frustule: producing mineral and organizing it into an elaborate wall are distinct experimental questions.