February 2018

Recombinant CYP Bactosomes: versatile formats for many ADME applications

Author:  Isabelle Nobiron, tebu-bio
Posted:  25 February 2018

Originally published in tebu-bio's Being Bioreactive. To purchase recombinant CYPs in the EU, please visit tebu-bio's website. For North American orders, please follow this link.
 

Recombinant CYPs are commonly used in ADME-Tox studies as in vitro tools, mostly for reaction phenotyping, enzyme inhibition screening, clearance and metabolite ID.

“Research has shown that rCYPs expressed in E. coli (Bactosomes) showed greater enzymatic activity compared with the equivalent enzymes expressed in insect cells (Supersomes). Similarly, most Bactosomes show greater turnover numbers when compared with the equivalent Supersomes. These results demonstrate that human rCYPs expressed in E. coli are frequently more active than the corresponding rCYPs expressed in insect cells» says Michael Voice from CYPEX.

If this statement from a CYP expert has encouraged you to learn more about CYPEX E. coli expressed CYPs (Bactosomes), this post should provide you with some clues on this interesting product range and how their flexibility in terms of formats can be an asset to suit your need.

What are the main features of Bactosomes?

  • Patented E. coli expression system
  • Excellent batch-to-batch consistency
  • High freezze/Thaw stability
  • Patented production method for native, or minimally modified P450’s
  • Robust P450 activity levels
  • Extensive batch-specific data (Km, Vmax, linearity with time and enzyme, at Km)
  • Comprehensive selection, including modified-reductase choices and controls
  • ISO9001:2009 compliant production and quality control
  • 10-30 minute linearity over time

What are the benefits of Bactosomes?

  • Bactosomes utilize native P450 and better represent human enzymes
  • Available with and without b5
  • Different levels of reductase allow for high and low activities
  • Reductase Bactosomes are optimized for metabolism
  • Low Reductase Bactosomes developed specifically for inhibition assays
  • Bactosomes exhibit the best linearity over time compared to competitor rCYPs
  • Least expensive commercial option
  • Extensive panel of P450s and Phase II expressed enzymes available
  • Only commercial source for recombinant dog P450s
  • Custom rCYPs available

Broad Linearity range: high and low reductase Bactosomes +/- b5 cytochrome

High and low reductase Bactosomes: The activity of many cytochrome P450s can vary significantly with the amount of NADPH P450 reductase available. Reductase (R) and High Reductase (HR) Bactosomes exhibit a limited linearity of substrate turnover with time. This is due to the fact that they contain high levels of NADPH P450 reductase, in turn creating higher activity. They may be better suited for metabolite profiling and reaction phenotyping. Low Reductase Bactosomes contain lower levels of NADPH P450 reductase, enhancing the linearity of substrate turnover with time making Bactosomes a perfect system for inhibition studies and more comparable to activities found in vivo. Whether you choose low or high reductase Bacotosomes will therefore depend on your application.

… with or without b5 Cytochrome: Addition of cytochrome b5 to bactosomes preparations has various effect depending on the assay conditions and which isoform is being used. For example use of CYP2E1 with cytochrome b5 is highly recommended as it reduces the Km for the reaction, but not necessarily always with CYP3A4 as the effect of b5 seems to disappear when the assay conditions are set to give high activity (that may not apply for a different substrate).

Cytochrome b5 activation of CYP3A4 activity is reductase (and buffer) dependent.

Data illustrating how cytochrome b5 activation of CYP3A4 activity is reductase (and buffer) dependent.
 

Flexible formats: EasyCYP standard vial size & Classic Bactosomes

Cypex EasyCYPs are a more convenient form of the bactosomes as they are standardised for CYP concentration (1nmol/mL) and protein concentration (10mg/mL). This means that, for routine assays, the volume to be added does not need to be recalculated for each different batch.

An example of all available formats discussed above is provided below for human CYP3A4 and human CYP-reductase coexpressed in Escherichia coli, with high or low reductase levels, supplemented or not with purified human cytochrome b5, each as standard or EasyCYP formats:

EasyCYPs and Classic Bactosomes - Cypex and tebu-bio

A table of all available CYPs and in which format – EasyCYPs and Classic Bactosomes – Cypex and tebu-bio


If you can’t find the CYP you are looking for, don’t hesitate to contact us. Customization can be possible!

Originally published in tebu-bio's Being Bioreactive. To purchase recombinant CYPs in the EU, please visit tebu-bio's website. For North American orders, please follow this link.

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