Haloperidol binding to monoclonal antibodies. Hypervariable region amino acid sequence determination

Area of Science:

• Immunology
• Structural Biology
• Pharmacology

Background:

• Monoclonal antibodies (mAbs) are crucial for targeted therapies.
• Understanding antibody-antigen interactions at a molecular level is essential for drug development.
• Haloperidol is a D-2 dopaminergic antagonist used in treating psychosis.

Purpose of the Study:

• To determine the primary amino acid sequences of five monoclonal antibodies (mAbs) that bind to haloperidol.
• To investigate the structural basis for the varying affinities of these mAbs to haloperidol.
• To correlate antibody sequence and structure with binding site architecture.

Main Methods:

• Isolation of immunoglobulin light and heavy chain mRNA from mAbs A-E.
• Gene sequencing using primer extension with dideoxynucleotides.
• Computer-based molecular modeling to analyze binding site architecture.

Main Results:

• Primary sequences of five anti-haloperidol mAbs were determined.
• Variations in hypervariable regions, including insertions and deletions, were identified.
• Two mAbs exhibited pocket-shaped binding sites due to long hypervariable loops.
• Three mAbs displayed groove-like binding sites resulting from deletions in the third heavy chain complementarity-determining region.

Conclusions:

• Antibody primary sequences dictate binding site architecture through variations in hypervariable regions.
• Specific sequence features, such as loop lengths and deletions, correlate with distinct binding site shapes (pocket vs. groove).
• These findings provide insights into the molecular mechanisms of antibody-antigen recognition for haloperidol.