Which digestion buffers are compatible with FabRICATOR HPLC?
We have tested PBS and 150 mM ammonium acetate, pH7 with good results. More buffers were found to be compatible with FabRICATOR digestion in solution (more info) and should be suitable for FabRICATOR HPLC as well. However, the ionic strength of the buffer influences retention of the antibody fragments on the FabRICATOR HPLC column and a minimum of 100-150 mM salt is necessary for IgG1 subunits to elute as a single, narrow peak. Other IgG subclasses or fusion proteins might need some optimization of buffer composition.
Can I use FabRICATOR HPLC in a 2D-LC setting?
Yes, it is possible to digest the antibody in the first dimension and then separate the subunits in the second dimension. Please see the application note for detailed instructions.
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.
Is GingisKHAN an IgG specific protease?
No, GingisKHAN is a general protease that with the recommended reaction conditions, 1 hour with light reducing conditions, digests human IgG1 at one specific site (…KSCDK/THTCPPCP…) above the hinge, generating Fab and Fc.
How can I stop the GingisKHAN reaction?
The enzyme is a cysteine protease that can be inhibited by alkylating agents such as iodoacetamide. There are also several other known inhibitors to this enzyme, like KYT-36.
Can I use another reducing agent besides GingisKHAN reducing agent?
We recommend using the 10x reducing agent provided with GingisKHAN which has an optimized pH to provide full enzymatic activity without affecting the disulphide bridges between the light chain and Fd region of the heavy chain, keeping the Fab intact. If other reducing agent is used there is a risk for non-optimal reaction conditions. It is important to use freshly prepared Reducing Agent (max storage 6h) for guaranteed activity of GinigsKHAN.
Can you recommend a protocol for purification of the Fab?
Genovis provides a GingisKHAN Fab kit containing a specific Capture Select CH1 resin for further purification of the Fab. See this page for more information.