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Activity of recombinant mitogillin and mitogillin immunoconjugates
M Better1, S L Bernhard, S P Lei
1XOMA Corporation, Santa Monica, California 90404.
The Journal of Biological Chemistry
|August 15, 1992
Summary
Researchers engineered the Aspergillus protein toxin mitogillin for enhanced immunotoxin development. Genetic modifications allow direct conjugation, creating potent protein synthesis inhibitors for targeted cancer therapy.
Area of Science:
- Molecular Biology
- Biochemistry
- Immunology
Background:
- Mitogillin is a potent protein synthesis inhibitor from Aspergillus.
- Native mitogillin contains cysteine residues crucial for its structure.
- Immunoconjugates are being explored for targeted cell killing.
Purpose of the Study:
- To synthesize and express a recombinant gene for Aspergillus protein toxin mitogillin.
- To investigate the activity of modified mitogillin derivatives in protein synthesis inhibition.
- To develop a novel method for creating immunotoxins without initial derivatization.
Main Methods:
- Gene synthesis and expression of recombinant mitogillin in E. coli.
- Creation of mitogillin derivatives by substituting cysteine residues with alanine.
- Conjugation of modified mitogillin to H65 antibody for immunotoxin formation.
Main Results:
- Recombinant mitogillin potently inhibited protein synthesis (IC50 of 9.7 pM).
- Mitogillin derivatives retained significant protein synthesis inhibitory activity.
- The mitogillinC147A derivative allowed direct conjugation to antibody, forming an active immunoconjugate.
Conclusions:
- Genetic manipulation of toxin genes can create accessible cysteine residues for immunotoxin generation.
- This approach bypasses the need for nonspecific cross-linking reagents in immunotoxin production.
- Engineered mitogillin derivatives offer a promising strategy for developing targeted immunotoxins.