1. How many custom proteins have you produced so far? What is the typical success rate?
We have made more than 150 custom proteins with a success rate of approximately 75% (yield at 4mg or more from 2-liter culture and purity at 75%).
2. What is guaranteed provided at the end of production? Do we have to pay even if there was no measurable protein produced or if the protein is still very dirty after your affinity purification?
There are two options in terms of protein production services:
Option 1): 3-5mg purified protein with 75% purity will be GUARANTEED. Otherwise no payment will be requested. The charge will be $3,100 for cloning, protein expression services, and purification in E. coli.
Option 2): You will get whatever amount of protein purified from 2 liters of culture
with our best-optimized procedure. But NEITHER YIELD NOR PURITY WILL BE GUARANTEED. The charge will be $1,800 for cloning, protein expression services, and purification.
3. Is payment due upon delivery, or before start of the project, or subject to milestones (e.g. 30% upfront, 30% upon proven production, 30% upon delivery of purified protein)?
We charge subject to milestone with 50% upfront and 50% upon the completion of the project.
4. Are purification conditions native or denatured (we prefer native)?
Most of them are denatured, although native is not excluded. If you select option 2), we could try the native condition without extra charge.
5. Do you offer a discount for His and GST tagged versions of the same protein (normally 2 x 1800 $)?
If you already have expression vector with His or GST and no new construction is needed, you will get $600 off from the original price. But we prefer to make new construction since we have more confident in using our own parent vectors for protein yield.
6. Will the final protein product have biological activity?
In most of cases, the protein will be purified from inclusion body and the activity has not been tested although the soluble form can be obtained sometimes. We could provide refolding service for with extra charge. Talk to our customer support for detail.
7. Why is the SDS-Page blot of the protein at a higher MW than what I expected to see?
Yes, the final size of a natural protein, produced in mammalian cells under normal circumstances is at the molecular weight reported in literature. However, we are making a recombinant protein, with 2 tags, and in yeast cells. More specifically, the gene of interest is tethered behind a signal peptide gene to enhance secretion in the yeast system. This signal peptide is (usually) cleaved off from the final protein. However, sometimes it isn’t, which results in the final protein being a bit larger than expected. (Note that whether the signal peptide is cleaved off or not is not predictable, as this is a biological process performed by the cells.) The extra residues may or may not change the functions of the protein.