Can I process diluted IgG samples using FabRICATOR HPLC?
We have tested concentrations as low 0.025 mg/ml without any measurable effect on digestion efficiency. However, low concentration samples require a longer injection time and consequently lead to a broader elution peak from the FabRICATOR HPLC column.
How many samples can I run through a column of FabRICATOR HPLC?
The FabRICATOR HPLC can run >400 samples of 10 ug of IgG.
Can I release Fc fragments from the CaptureSelect column after isolating the F(ab’)2 fragments?
It is possible to elute the Fc fragments from the CaptureSelect column using a low pH buffer, for example a 0.1M Glycine buffer pH=3.0. The pH must immediately after elution be adjusted to neutral pH by adding 0.1x elution volume of 1M Tris pH=8.0.
Can I use protein A or MabSelectSure (GE) for removal of Fc-fragments?
Genovis has chosen CaptureSelect in the FabRICATOR Fab2 Kit for removal of Fc fragments. CaptureSelect has a very high specific affinity for the Fc. Both protein A and MabSelect Sure (GE) may have affinity for the Fab which may result in a lower recovery of the generated F(ab’)2 fragments and the degree of affinity is antibody dependent. We have many customer reports on this subject, and they usually come back to us for the CaptureSelect columns for the above reason.
Can I cleave Fc-fusion proteins with FabRICATOR?
Yes, FabRICATOR should be able to digest a Fc fusion protein as long as you have not fused the protein too close to the cleavage site. FabRICATOR digests human IgG just below the hinge (…CPAPELLG / GPSVF…), leaving the hinge on the fusion-part.
Is it possible to use FabRICATOR in a buffer containing EDTA or HSA?
Yes. FabRICATOR is compatible with EDTA. Make sure your pH is within 6-8.
How much of the FabRICATOR do you need to cleave IgG in 50 µl of normal human serum?
If we assume that the antibody concentration in serum is 15 mg/ml you would have to add 10-15 000 units to a sample of 1 ml serum. In 50 µl serum you would have to add 500 – 750 units of FabRICATOR.
Where does FabRICATOR cleave the IgG molecule?
FabRICATOR® cleave the IgG molecule in one specific site in the lower hinge region of the anitbody leaving a F(ab’)2 fragment and a Fc-fragment.
Human IgG1: ..CPAPELLG / GPSVF..
Human IgG2: ..CPAPPVA / GPSVF..
Human IgG3: ..CPAPELLG / GPSVF..
Human IgG4: ..CPAPEFLG / GPSVF..
Does FabRICATOR (IdeS) have protease activity on IgM?
No. According to the following reference, FabRICATOR does not digest IgM. Pavel-Rammingen et al., 2002. IdeS, a novel streptococcal cysteine proteinase with unique specificity for immunoglobulin G.
Does FabRICATOR introduce modifications?
FabRICATOR is a cysteine protease. It should not result in any other modifications than the digestion of the peptide bond. Digestion will be between the two Glycines (…CPAPELLG / GPSVF…) and the C-terminus will regain the carboxyl group – that is addition of one OH-group and the N-terminal amino group will be regained (addition of one H).
In summary, R1-CO-NH-R2 + H2O –> R1-COOH + NH2-R2.