FabULOUS® (SpeB)

FabULOUS (SpeB) is a recombinantly produced cysteine protease that under reduced conditions digests in the hinge region of antibodies from many species and subclasses, including human, mouse, rat and goat.


FabULOUS is available in two product formats:

  • FabULOUS Enzyme - lyophilized enzyme
  • FabULOUS Fab kit - lyophilized enzyme and affinity purification resin for easy generation and purification of Fab fragments from mouse IgG. 

Product Information

FabULOUS (SpeB) is an enzyme for digestion of IgG in the hinge region. All subclasses of human, mouse, rat, goat and sheep IgG are digested by FabULOUS, yielding Fab and Fc fragments. The primary digestion site on human IgG1 is ..KTHT / CPPCPAPE.. and on mouse IgG1 ..KPCIC / TVPEVS..

FabULOUS is derived from Streptococcus pyogenes and is expressed in E. coli. The molecular weight of FabULOUS is 28 724 Da and the enzyme contains a His-tag.

Key Characteristics

  • Human IgG1-4, IgG from mouse, rat, goat, sheep and rabbit
  • 60 min reaction
  • Requires reducing conditions
  • Human IgG1: KTHT / CPPCPAP (above the hinge)


Purified and homogenous Fab fragments can be used in many applications, including:

  • Study monovalent binding of Fab fragments to the antigen
  • Elimination of Fc-mediated effector functions
  • Reduced unspecific binding from Fc interactions

Product Formats

FabULOUS® Enzyme

FabULOUS enzyme supplied as lyophilized powder. The enzyme is available in a 2000 unit vial (1 unit digests 1 ug IgG).

FabULOUS® Fab kit mouse

FabULOUS Fab kit mouse is used for rapid and easy preparation and purification of Fab fragments from mouse IgG. The kit consists of two parts; lyophilized FabULOUS enzyme and affinity spin columns for purification of intact Fab fragments.

Latest References using this Product


Brochures and Posters

Download Genovis brochures and posters with the latest details on the SmartEnzymes

Smart Enzyme Reference Tool

SmartEnzyme Reference Tool

Find the right reference for the antibody attribute you are studying



Learn more about the applications of Genovis SmartEnzymes

Download FabULOUS Poster

Antibody Characterization

CASSS 2013

"Initial Characterization of a Recombinantly Modified SpeB from S. pyogenes for Antibody Subunit Domain Generation"

FAQ and Support


Yes, but a longer incubation time is needed.

Find all FAQ here

Product Documents

Patent and Disclaimer


All rights reserved. The trademark FabULOUS is the property of Genovis AB. 

For research use only. Not intended for any animal or human therapeutic diagnostic use.

©2018 Genovis AB.