Vasoactive intestinal peptide hydrolysis by antibody light chains.
This paper describes evidence for hydrolysis of a neuropeptide, vasoactive intestinal peptide (VIP), by light chains purified from the IgG of a human subject positive for VIP binding antibodies. Purified IgG was digested with papain, resultant fragment antigen binding (Fab) fragments were reduced with 2-mercaptoethanol and alkylated with iodoacetamide, and light chains were purified by chromatography on immobilized antibodies to light chains and immobilized antibodies to heavy chains. Non-immunoglobulin components were undetectable in the light chain preparation, judged by sodium dodecyl sulfate-electrophoresis and Western blotting with anti-heavy and anti-light chain antibodies. The light chains hydrolyzed VIP with specific activity 32-fold greater than that of Fab, the pH optimum for light chain-mediated VIP hydrolysis was 7.0-7.5, and the hydrolytic activity was saturable (Vmax, 0.19 pmol/min/microgram light chains; substrate concentration at Vmax/2,380 nM).
Mei
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S
Department of Pharmacology, University of Nebraska Medical Center, Omaha 68198-6260.
Mody
B
B
Eklund
S H
SH
Paul
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S
D001345:Autoradiography; D002851:Chromatography, High Pressure Liquid; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D006868:Hydrolysis; D007140:Immunoglobulin Fab Fragments / Q000378:metabolism; D007147:Immunoglobulin Light Chains / Q000378:metabolism*; D014660:Vasoactive Intestinal Peptide / Q000378:metabolism*
D007140:Immunoglobulin Fab Fragments; D007147:Immunoglobulin Light Chains; D014660:Vasoactive Intestinal Peptide