Silaffins of Diatoms: From Applied Biotechnology  to Biomedicine

Pamirsky, I. E.; Golokhvast, Kirill S.

doi:10.3390/md11093155

Cited by 48 publications

(38 citation statements)

References 41 publications

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“…However, it can also be seen in this figure that the addition of the R5 peptide provides a tailored affinity site for silica, thereby incorporating a more selective immobilization capability for the protein without requiring additional chemical coupling reagents. R5 belongs to the proteins rich in arginine and lysine involved in silica precipitation (silaffins [30,[33][34][35]). By adding the 19-amino acid R5 sequence (SSKKSGSYSGSKGSKRRIL) to mCherry the estimated pI for the protein shifts positive by ~1 unit for each R5 peptide unit added [36], due to the positively charged residues on the R5 polypeptide (K and R) [37].…”

Section: Silica Integrationmentioning

confidence: 99%

Gene to diagnostic: Self immobilizing protein for silica microparticle biosensor, modelled with sarcosine oxidase

et al. 2019

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A rational design approach is proposed for a multifunctional enzyme reagent for point-of-care diagnostics. The biomaterial reduces downstream isolation steps and eliminates immobilization coupling chemicals for integration in a diagnostic platform. Fusion constructs combined the central functional assay protein (e.g. monomeric sarcosine oxidase, mSOx, horseradish peroxidase, HRP), a visualizing protein (e.g. mCherry) and an in-built immobilization peptide (e.g. R5). Monitoring protein expression in E.coli was facilitated by following the increase in mCherry fluorescence, which could be matched to a color card, indicating when good protein expression has occurred. The R5 peptide (SSKKSGSYSGSKGSKRRIL) provided inbuilt affinity for silica and an immobilization capability for a silica based diagnostic, without requiring additional chemical coupling reagents. Silica particles extracted from beach sand were used to collect protein from crude protein extract with 85-95% selective uptake. The silica immobilized R5 proteins were stable for more than 2 months at room temperature. The Km for the silica-R52-mCh-mSOx-R5-6H was 16.5±0.9mM (compared with 16.5±0.4 mM, 16.3±0.3 mM, and 16.1±0.4 mM for R52-mCh-mSOx-R5-6H, mSOx-R5-6H and mSOx-6H respectively in solution). The use of the "silica-enzymes" in sarcosine and peroxide assays was shown, and a design using particle sedimentation through the sample was examined. Using shadowgraphy and particle image velocimetry the particle trajectory through the sample was mapped and an hourglass design with a narrow waist shown to give good control of particle position. The hourglass biosensor was demonstrated for sarcosine assay in the clinically useful range of 2.5 to 10 µM in both a dynamic and end point measurement regime.

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Section: Silica Integrationmentioning

confidence: 99%

Gene to diagnostic: Self immobilizing protein for silica microparticle biosensor, modelled with sarcosine oxidase

et al. 2019

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“…Besides classic applications of silica as absorbent, stationary phase in liquid chromatography, catalysis or general filling material, it also finds increasing implementation as an additive in cosmetics and in the food industry since it is generally recognized as safe [ 84 , 85 ]. The progress in syntheses of silica materials with defined structures and properties and the development of novel routes for biomimetic silica formation have prompted the application of silica based materials particularly in biotechnology and biomedicine [ 86 , 87 , 88 , 89 ].…”

Section: Biotechnological Applications Of Silicamentioning

confidence: 99%

Silaffins in Silica Biomineralization and Biomimetic Silica Precipitation

2015

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Biomineralization processes leading to complex solid structures of inorganic material in biological systems are constantly gaining attention in biotechnology and biomedical research. An outstanding example for biomineral morphogenesis is the formation of highly elaborate, nano-patterned silica shells by diatoms. Among the organic macromolecules that have been closely linked to the tightly controlled precipitation of silica in diatoms, silaffins play an extraordinary role. These peptides typically occur as complex posttranslationally modified variants and are directly involved in the silica deposition process in diatoms. However, even in vitro silaffin-based peptides alone, with and without posttranslational modifications, can efficiently mediate biomimetic silica precipitation leading to silica material with different properties as well as with encapsulated cargo molecules of a large size range. In this review, the biomineralization process of silica in diatoms is summarized with a specific focus on silaffins and their in vitro silica precipitation properties. Applications in the area of bio- and nanotechnology as well as in diagnostics and therapy are discussed.

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“…These proteins are involved in the formation of the elegant silica structures observed in these organisms. Furthermore, the addition of silaffin and silicatein to a silicic acid precursor solution in vitro results in the formation of silica under ambient conditions [13][14][15][16]. On the other hand, synthetic polyamines and cationic poly( L -lysine) were able to catalyze silicic acid deposition [17][18][19][20][21][22][23].…”

Section: Introductionmentioning

confidence: 99%

Silica–enzyme–ionic liquid composites for improved enzymatic activity

Kato

Kawachi

Nakamura

2014

Journal of Asian Ceramic Societies

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Trypsin and pepsin enzyme-catalyzed precipitation of silica, synthesized by sol-gel chemistry in an ionic liquid, produces a composite material that demonstrates high enzymatic activity. This study investigates the structural properties of this silica-enzyme-ionic liquid composite material that allows for the retention of enzyme hydrolysis and condensation activity. The composite was prepared from a mixture of organo-functionalized triethoxysilane and tetraethoxysilane in an ionic liquid via enzyme-catalyzed direct hydrolysis and polycondensation reactions. The composite samples have been fully characterized with SEM, TEM, TG-DTA, IR, and N 2 isotherms, and incorporation of the composite's organic function has been demonstrated by 29 Si and 13 C nuclear magnetic resonance. The presented systematic approach provides valuable information on the influence of the enzyme and ionic liquid on the properties of the silica gel and nature of the silica network as well as on the extent of enzyme and ionic liquid encapsulation. SEM and TEM reveal that the silica-enzyme-ionic liquid composites prepared from trypsin are composed of an aggregate of closely packed spherical structures ∼20 nm in diameter; however, the composites from pepsin consist of larger particles of ∼1 m having a smooth surface. In addition, after encapsulation within the silica-ionic liquid composite, enzymes showed extremely high hydrolysis and condensation activities using trimethylethoxysilane as an enzyme substrate, and these activities were better than those of corresponding free enzyme solutions. The simple route employed can yield materials with high enzymatic activities, and this may offer very promising application prospects.

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Silaffins of Diatoms: From Applied Biotechnology to Biomedicine

Cited by 48 publications

References 41 publications

Gene to diagnostic: Self immobilizing protein for silica microparticle biosensor, modelled with sarcosine oxidase

Gene to diagnostic: Self immobilizing protein for silica microparticle biosensor, modelled with sarcosine oxidase

Silaffins in Silica Biomineralization and Biomimetic Silica Precipitation

Silica–enzyme–ionic liquid composites for improved enzymatic activity

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