Invited Paper BI-MoM8
Protein Catalysis of Minerals and Ice – A Molecular View

Monday, December 3, 2018, 10:20 am, Room Naupaka Salon 6-7

Proteins can act as Nature’s engineers at interfaces and manipulate both hard and soft tissue – they can shape biominerals, manipulate cell membranes and control water. Despite the apparent importance for chemists working in the fields of biomineralization, surface engineering and drug delivery the molecular mechanisms behind interfacial protein action have largely remained elusive. We use static and time resolved sum frequency generation spectroscopy combined with computer simulations to determine the structure and the mode of action by which these proteins interact with and manipulate interfaces. Here, I discuss our recent advances in the study of protein driven nucleation.

Taking clues from Nature we aim at understanding biomineralization processes at the molecular level to develop design rules for biogenic nanophase materials. Especially the high fidelity control of nanostructured silica within diatoms has been the envy of material scientists for decades. Where diatoms can grow silica using proteins at cell interfaces under ambient conditions, we still need high pH and harsh conditions to structure silica. Despite the apparent importance for physicists and chemists working in the fields of biomineralization, surface engineering, drug delivery, or diagnostics, the molecular mechanisms behind interfacial silica protein action have remained largely elusive. Our goal is to probe the structure and structural dynamics of such active proteins – in action at the surface. As a first step we study the diatom silica peptide R5 when interacting with silica. We use methods based on theoretical and experimental sum frequency generation spectroscopy combined with computer simulations to determine the structure and the mode of action by which these proteins interact with and grow extended 2D silica interfaces.

A particularly fascinating example of protein driven nucleation and phase transitions are ice-nucleating proteins. These proteins are used by specific bacteria to attack plants and cause frost damage by growing ice crystals at temperatures that would otherwise not allow ice formation. A recent survey by the NASA found that biogenic ice nucleators in the troposphere may affect global precipitation patterns. We have followed the interaction of biogenic ice seeding proteins with surrounding water to gain a detailed picture of protein-driven ice nucleation.