Structural studies on proteins using nuclear magnetic resonance (NMR) require labelling of these molecules with stable isotopes. Organisms such as bacteria and yeast are used to express the proteins. Silantes offers a wide range of stable isotope-labelled cell growth media to express stable isotope-labelled proteins.
Available in Multiple Variations, Tailored to Your Needs
Depending on your application and purpose, we offer different media variations for the expression of stable isotope-labelled proteins in E.coli and yeast. Yeast is used for the expression of eukaryotic proteins, since this host facilitates a high protein expression and many post-translational protein modifications which are characteristic for mammalian cells.
Silantes also offers stable isotope labelled reagents for M9 media such as 13C-glucose, D2O and 15NH4Cl.
High Standards in Quality Control
The Silantes media are validated for reproducible fermentation results. Moreover, each batch is adjusted to guarantee consistent cell densities. The media are available in all combinations of the isotopic labels 2H, 13C, 15N with an isotopic enrichment of > 98 %. This isotopic enrichment is validated by mass spectrometry. The biological competence is validated in growth tests. The results of the quality control are included in each delivery.
No Additional 13C-glucose Needed
All Silantes products are prepared from uniformly labelled bacterial cell hydrolysate of Ralstonia eutropha. If the media are used as stand-alone media, no additional 13C-glucose needed in order to express 13C-labelled proteins.
The Silantes OD2 Solution Medium is the high-performance line amongst the range of Silantes stable isotope-labelled cell growth media for the expression of stable isotope-labelled proteins.
Ready-to-Use Rich Growth Medium
The Silantes OD2 media are rich growth media solutions. They are sterile and ready-to-use for fermentation purposes. The media are made from isotopically labelled bacterial hydrolysate and contain primarily amino acids, some low molecular weight oligopeptides and almost no carbohydrates. The bacterial strain used is a chemolithoautotrophic organism which grows on isotopically labelled inorganic substrates.
Quote by Dr. Leonardo Gonnelli, CERM, Centro di Risonanze Magnetiche, Universita di Firenze, Italy:
"Protein expression can be easily optimized in Silantes medium and often the best conditions found in LB standard medium can be used. Silantes saves your time! Silantes media are an excellent opportunity to get labelled samples for MR studies, especially if you need a fast preparation for high-throughput targets. Today, most of the labelled samples of our lab are prepared using Silantes media."
Excellent Performance, Especially in D2O
The Silantes OD2 solution medium is developed for a high-performance expression of stable isotope labelled proteins. The media are adjusted in salt conditions formulated for a > OD600 2 cell density. They can be used to grow organisms in H2O or D2O, the latter with a 4-fold delay.
Figure 1 shows the growth curve of E.coli in 2H-labelled Silantes OD2 Solution Medium for E.coli and in 1 % unlabelled Silantes SILEX Powder Medium for E.coli in D2O. The figure shows that both media have the same excellent performance in D2O and exceed OD 2.5 in less than 24 hours.
Figure 1: Growth of E.coli 2H-labelled Silantes media solution and in Silantes powder media in D2O
Quote by Prof. Dr. Harald Schwalbe, Johann Wolfgang-Goethe-Universität, Frankfurt, Germany:
"We have used Silantes expression media for protein expression. The yields were with the first trial superior to our results using minimal medium. I can strongly recommend using the products by Silantes."
Quote by Dr. Stefan Prytulla, M-Phasys, Tübingen, Germany:
"After purification, we obtained about 35 mg of pure protein with the D15N-labelled Silantes OD2 Media. This is even a few milligrams more than we usually get from LB cultures. "
Figure 2 and figure 3 show SDS-PAGEs as an example of protein expressions using M9 medium and Silantes OD2 Solution Medium. The proteins are ubiquitin and RNA polymerase α-subunit. The figures show the enhanced yield using Silantes OD2 Solution Medium.
Figure 2 and Figure 3: SDS-PAGE of Ubiquitin (left) and SDS-PAGE of RNA-Polymerase a-subunit
Quote by Dr. Klaus Fiebig, Frankfurt University, Frankfurt, Germany:
"We compared Silantes unlabelled media with Silantes 13C15N-labelled media and found no substantial differences in growth or expression rates. We have enclosed data of a typical growth curve and the resulting protein yield obtained in the same system, using 15N-labelled M9 medium. Silantes media give extraordinarily high results compared to common M9 media."
Quote by Prof. Sklenar, Masaryk University, 2001:
"The result (of the Silantes OD2 Media) was comparable to typical rich growth media, the yield (expression of MUP1) of the Silantes OD2 Media was two-times higher; the growth parameters were good. Silantes OD2 Media are very convenient to use."
Silantes SILEX and ECO are powder media providing high flexibility in experiments for expression of stable isotope labelled proteins. Both powder media can be used as stand-alone media or as a supplement in M9 fermentations.
Diagram 3 shows that the powder medium added as a supplement to M9 medium increases the initial cell-growth rate. The supplement was 1 g 15N-labelled SILEX powder per liter and the "stand-alone medium" was 10 g 15N-labelled SILEX powder per liter.
Figure 3: Growth of E.coli in different media
SILEX Powder Media for High Performance
The SILEX powder is lyophilized from the High Performance OD2 Rich Growth Solution Medium (see above) which are made from isotopically labelled bacterial hydrolysate containing primarily amino acids, somelow molecular weight oligopeptides and almost no carbohydrates.
Therefore, Silantes SILEX Powder Media are designed to provide high cell growth rates and high protein expression yields.
This excellent performance also extends to cell growth in deuterated conditions: Figure 1 (see above) shows that the SILEX powder used as a stand-alone Medium (10 g/L) in D2O exceed OD 2.5 in less than 24 hours.
The ECOnomic Alternative
The Silantes ECO powder media are a more economic alternative to SILEX powder media. They contain the same ingredients as the SILEX powder while having a slightly higher amount of low molecular weight oligopeptides.
Economic concept: 13C- or 13C15N-labelled Silantes ECO Media are more economical than classic M9 fermentations using 13C-glucose and/or 15N-ammonium.