Frequently Asked Questions
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Can I re-use FabRICATOR Z Immobilized columns?
We can only guarantee optimal digestion for one-time use. We do not have a cleaning or regeneration protocol to provide. However, depending on the antibody and the following application the column can be reused. We do not recommend using with different antibodies due to the risk for contamination of carry-over from previous sample. If column reuse is desired store the column in 10-20% ethanol at +4-8°C.
Learn more about FabRICATOR®, FabRICATOR® Z
What is the difference between FabALACTICA and GingisKHAN?
FabALACTICA (IgdE) and GingisKHAN (Kgp) are both cysteine proteases that digest IgG1 above the hinge to generate intact Fab and Fc fragments. FabALACTICA is specific for human IgG1 and digests at a specific site (…KSCDKT / HTCPPCP…) with overnight incubation without the need for reducing conditions. GingisKHAN is a general protease that with the recommended reaction conditions, 1 hour with light reducing conditions, digests human IgG1 at a specific site (…KSCDK/THTCPPCP…).
Learn more about FabALACTICA™, GingisKHAN™
How can I remove residual enzyme from the digested antibody in solution?
We recommend using FabALACTICA Immobilized for digesting human IgG1 and generating a final preparation free of any residual enzyme. You can also use FabALACTICA Fab kit for digestion of human IgG1 and purification of the generated Fab fragments.
Learn more about FabALACTICA™
Can I digest Fc-fusion proteins using FabALACTICA (IgdE)?
No, FabALACTICA has shown very poor activity on Fc-fusion proteins.
Learn more about FabALACTICA™
Can I re-use FabALACTICA Immobilized columns?
We can only guarantee optimal digestion for one-time use. We do not have a cleaning or regeneration protocol to provide. However, depending on the antibody and the following application the column can be reused. We do not recommend using with different antibodies due to the risk for contamination of carry-over from previous sample. If column reuse is desired store the column in 10-20% ethanol at +4-8°C.
Learn more about FabALACTICA™
Can I release Fc fragments from the CaptureSelect column after isolating the Fab fragments?
It is not recommended to elute the Fc fragments from the CaptureSelect column since the fraction might also include undigested or semi digested material.
Learn more about FabALACTICA™
Can I use GingisKHAN on other subclasses than human IgG1?
No. GingisKHAN is a protease that digests at exposed Lysines with no secondary structure restrictions. At the recommended reaction conditions, GingisKHAN digestion above the hinge has only been confirmed on human IgG1 with the exposed lysine above the hinge, (…KSCDK / THTCPPCP…). No digestion has been confirmed on other subclasses of human IgG except for several digestion sites in human IgG3.
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Is it possible to prepare Fab fragments from different antibodies using GingisKHAN Fab kit?
Yes. GingisKHAN is provided lyophilized. After reconstitution, the enzyme can be used for up to 4 different antibodies. The digestion is performed in solution and you can prepare Fab fragments from 4 x 0.5 mg human IgG1. The purification step is done with Capture Select columns and 4 columns are provided in the kit.
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Does FabULOUS digest all human IgG subclasses above the hinge?
FabULOUS is a cysteine protease that digests IgG in the hinge region. A primary digestion site for human IgG1 is above the hinge (…KTHT / CPPCP…). The enzyme is also active on human IgG2 and IgG3, digestion site not determined but Fab and Fc is generated. FabULOUS digests human IgG4 primarily at a site below the hinge using significantly longer incubation, generating Fab’ due to the reducing conditions. The possibility of other, secondary digestions sites is antibody dependent
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Will the reducing conditions required for digestion impact the interchain disulfide bond integrity?
Depending on what reducing agent and what concentration you use you can obtain intact Fab and not reduce the interchain disulfide bond. The light chain (LC) and heavy chain (HC) will not dissociate under native conditions due to hydrogen/hydrophobic forces. Before you analyze your samples with SDS-PAGE you must remove the cysteine otherwise the Fab will be reduced to Fd and LC during sample preparation for the SDS-PAGE. This can be done by a simple buffer exchange.
Learn more about FabULOUS™
