Metal-dependent amyloid β-degrading catalytic antibody construct

Area of Science:

• Biochemistry
• Immunology
• Structural Biology

Background:

• Catalytic antibodies (catabodies) capable of rapid antigen degradation are uncommon.
• Amyloid-beta peptides (Aβ) are implicated in neurodegenerative diseases.

Purpose of the Study:

• To investigate the metal-dependence of a novel catabody, construct 2E6, engineered to hydrolyze Aβ.
• To elucidate the role of metal cofactors in catabody catalytic activity.

Main Methods:

• Characterization of catabody 2E6 activity using Aβ hydrolysis assays.
• Inhibition studies with metal chelators (EDTA, 1,10-phenanthroline) and electrophilic phosphonate inhibitors.
• Metal ion restoration experiments (Zn(2+), Co(2+)) and fluorescence emission spectroscopy to monitor conformational changes.

Main Results:

• Metal chelators completely inhibited Aβ hydrolysis by catabody 2E6.
• EDTA inactivation prevented Aβ disaggregation, highlighting the importance of hydrolytic activity.
• Restoration with Zn(2+) or Co(2+) reactivated catabody activity, with Zn(2+) inducing conformational changes.

Conclusions:

• The catalytic activity of catabody 2E6 is absolutely dependent on a metal cofactor.
• Metal ions play a crucial role in the catalytic mechanism of Aβ hydrolysis by this engineered antibody.