ABSTRACT
Nature is an exquisite designer of inorganic materials using biomolecules as templates. Diatoms create intricate silica wall structures with fine features using the protein family of silaffins as templates. Marine sponges create silica spicules also using proteins, termed silicateins. In recent years, our group and others have used biomolecules as templates for the deposition of inorganic materials. In contrast with the traditional materials science approach, which requires high heat, extreme pH and non-aqueous solutions, the bio-based approaches allow the reactions to proceed usually at near ambient conditions. Additionally, the biological templates allow for the control of the inorganic nanoparticle morphology. The use of peptides and biomolecules for templating and assembling inorganics will be discussed here.
Subject(s)
Chemistry, Bioinorganic/methods , Inorganic Chemicals/chemical synthesis , Amino Acid Sequence , Animals , Gold/chemistry , Inorganic Chemicals/chemistry , Microscopy, Electron , Nanoparticles/chemistry , Nanoparticles/ultrastructure , Nanostructures/chemistry , Nanotechnology , Oligopeptides/chemistryABSTRACT
Over the past decade antifreeze proteins from polar fish have been shown either to stabilize or disrupt membrane structure during low temperature and freezing stress. However, there has been no systematic study on how membrane composition affects the interaction of antifreeze proteins with membranes under stress conditions. Therefore, it is not possible at present to predict which antifreeze proteins will protect, and which will damage a particular membrane during chilling or freezing. Here, we analyze the effects of freezing on spinach thylakoid membranes and on model membranes of varying lipid composition in the presence of antifreeze protein type I (AFP I) and specific fractions of antifreeze glycoproteins (AFGP). We find that the addition of galactolipids to phospholipid model membranes changes the effect each protein has on the membrane during freezing. However, the greatest differences observed in this study are between the different types of antifreeze proteins. We find that AFP type I and the largest molecular weight fractions of AFGP induce concentration dependent leakage from, and are fusogenic to the liposomes. This is the first report that an antifreeze protein induces membrane fusion. In contrast, the smallest fraction of AFGP offers a limited degree of protection during freezing and does not induce membrane fusion at concentrations up to 10 mg/ml.
