You could use recombinant proteins from different companies for your ELISAs, however keep the following in mind:
- Protein tags are useful for protein purification.
- Recombinant proteins expressed from E.coli from the same source can show greater than 10 fold difference in terms of immunoreactivity from lot to lot, primarily due to refolding inconsistency.
- Different kit standards can be produced and calibrated against different references. So far there is no universally accepted standardization for recombinant protein immunoreactivities.
- Any changes to the reagents (standards, antibodies, matching matrices) and protocols may affect the final assay performance.