Peptides diatoms

Kroger N, Deutzmann R, Sumper M (1999) Polycationic peptides from diatom biosilica that direct silica nanosphere formation. Science 286 1129-1132... 

Some non-silica sol-gel materials have also been developed to immobilize bioactive molecules for the construction of biosensors and to synthesize new catalysts for the functional devices. Liu et al. [33] proved that alumina sol-gel was a suitable matrix to improve the immobilization of tyrosinase for detection of trace phenols. Titania is another kind of non-silica material easily obtained from the sol-gel process [34, 35], Luckarift et al. [36] introduced a new method for enzyme immobilization in a bio-mimetic silica support. In this biosilicification process precipitation was catalyzed by the R5 peptide, the repeat unit of the silaffin, which was identified from the diatom Cylindrotheca fusiformis. During the enzyme immobilization in biosilicification the reaction mixture consisted of silicic acid (hydrolyzed tetramethyl orthosilicate) and R5 peptide and enzyme. In the process of precipitation the reaction enzyme was entrapped and nm-sized biosilica-immobilized spheres were formed. Carturan et al. [11] developed a biosil method for the encapsulation of plant and animal cells. 

This is a silica-based support (85-90% Si02) containing alumina (3-6%) and can be found in nature in the form of fossilized diatoms. This type of support has found primary usage in both continuous-flow oligonucleotide and peptide synthesis. Typical loadings are in the range of 0.05-0.13 mmol amine/g and go by the names NovaSyn KD (Calbiochem-Novabiochem Corp.) or Macrosorb K (Phase Separations Ltd.) [31],... 

B. Polycationic Peptides Occluded in Diatom Biosilica Accelerate Silicic... 

Many other polyamines are known. Among these are a 4-aminobutylcadaverine isolated from root nodules of the adzuki bean and very long partially aromatic hydroxylamine derivatives from venom of common funnel-web spiders (structures at top of page). Cationic polypeptides called silaffins, with masses of 3 kDa, apparently initiate the growth of the silica cell walls of diatoms (Box 4-B). These peptides contain polyamines consisting of 6 to 11 repeated N-methylpropylamine imits covalently attached to lysine residues and also many phosphoserines. ... 

Synthetic Peptides Derived from the Diatom Cylindrotheca fusiformisi Kinetics of Silica Formation and Morphological Characterization... 

It is well known that a variety of organisms are able to produce intricately patterned species-specific siliceous materials and that they are able to do so with great fidelity. In order to understand the role(s) that biomolecules play in the formation of nano- and micro-structured biosilica, organic material associated with biosilica has been isolated, identified and studied. To date, the main focus has been a variety of investigations of R5 (in both its modified and unmodified forms) and its ability to form silica in vitro. The R5 peptide is a nineteen amino acid sequence which corresponds with silaffin-lAi of the diatom Cylindrotheca fusiformis. In order to study the role of biomolecules in (bio)silicification, we have chosen to systematically study the silica forming ability of three peptides derived fi om the diatom C. fusiformis - namely, Rl, R2, and R5. The R1 peptide is a thirty three amino acid... 

Kroger, N. Deutzmann, R. Sumper, M., Silica-precipitating peptides from diatoms - The chemical structure of silaffin-lA from Cylindrotheca fiisiformis. J. Biol. Chem. 2001,276, (28), 26066-26070. 

The distributed multipole model automatically includes non-spherical, anisotropic effects due to features such as lone pairs or tt electrons. The original applications of the DMA approach were to small molecules such as diatomics and triatomics. The method has since been used to develop models for nuclei acids and for peptides and has even been applied to the undecapeptide cyclosporin [Price et al. 1989], which contains 199 atoms (the... 

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