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]
Polycationic peptides from diatom biosilica that direct silica nanosphere formation by N. Kröger and others. Abstract, Science 286, pp. 1129–1132
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. New to topics? Read the docs here!