Improvement of catalytic antibody activity by protease processing

Area of Science:

• Biochemistry
• Immunology
• Enzymology

Background:

• Immunoglobulin light chains play crucial roles in antibody structure and function.
• Enzymatic modification of proteins can alter their biological activity and properties.
• Lysyl-endopeptidase is a protease that cleaves peptide bonds at lysine residues.

Purpose of the Study:

• To investigate the effect of lysyl-endopeptidase treatment on the catalytic activity of an immunoglobulin L chain (HIR).
• To characterize the enzymatic properties of the resulting protein fragment.
• To explore the impact of this enzymatic processing on other Bence Jones proteins and complete antibodies.

Main Methods:

• Treatment of immunoglobulin L chain (HIR) with lysyl-endopeptidase.
• Gel filtration chromatography to isolate protein fragments.
• Enzyme kinetics assays (Km and Kcat determination) using Chromozym TRY hydrolysis.
• Analysis of five different Bence Jones proteins (BJPs) and complete antibodies.

Main Results:

• Lysyl-endopeptidase treatment yielded an 11 kDa VL fragment of HIR with significantly higher specific catalytic activity.
• The VL fragment exhibited altered kinetic parameters (Km and Kcat) compared to the original HIR.
• Elevated catalytic activity was observed in three out of five BJPs and in the complete antibody after enzymatic processing.

Conclusions:

• Enzymatic cleavage by lysyl-endopeptidase can enhance the catalytic activity of immunoglobulin L chain fragments.
• The VL fragment of HIR demonstrates potent catalytic properties.
• Lysyl-endopeptidase processing represents a potential method for modulating the enzymatic activity of immunoglobulins and related proteins.