Efficient vasoactive intestinal polypeptide hydrolyzing autoantibody light chains selected by phage display

Sonia Tyutyulkova, Qing Sheng Gao, Austin Thompson, Steven Rennard, Sudhir Paul

Research output: Contribution to journalArticle

45 Scopus citations

Abstract

An immunoglobulin light chain (L chain) library derived from the peripheral blood lymphocytes of a patient with asthma was cloned into a phagemid vector. Phage particles displaying L chains capable of binding vasoactive intestinal polypeptide (VIP) were isolated by affinity chromatography. Two VIP binding L chains were expressed in Escherichia coli in soluble form and purified to electrophoretic homogeneity by metal chelating and protein L affinity chromatography. Both L chains catalyzed the hydrolysis of [tyr10-125I]VIP substrate. The catalytic activity eluted at the molecular mass of the monomer form of the L chain (28 kDa) from a gel filtration column. The activity was bound by immobilized anti-κ-chain antibody. A control recombinant L chain displayed no catalytic activity. Hydrolysis of VIP by the catalytic L chains was saturable and consistent with Michaelis-Menten kinetics. The turnover of the L chains was moderate (0.22 and 2.21/min) and their K(m) values indicated comparatively high affinity recognition of VIP [111 and 202 nM), producing catalytic efficiencies comparable to or seater than trypsin. Unlike trypsin, the L chains did not display detectable cleavage of casein, suggesting a catalytic activity specialized for VIP. Comparisons of the nucleotide sequences of the L chain cDNA with their putative germ-line counterparts suggested the presence of several replacement mutations in the complementarity determining regions (CDRs). These observations suggest: (a) Retention or acquisition of catalytic activity by the L chains is compatible with affinity maturation of antibodies; and (b) The autoimmune L chain repertoire can serve as a source of substrate-specific and efficient catalysts.

Original languageEnglish (US)
Pages (from-to)217-223
Number of pages7
JournalBiochimica et Biophysica Acta - Molecular Basis of Disease
Volume1316
Issue number3
DOIs
StatePublished - Aug 23 1996

Keywords

  • Asthma
  • Autoantibody
  • Catalytic antibody
  • Light chain
  • Phage display
  • Vasoactive intestinal polypeptide

ASJC Scopus subject areas

  • Molecular Medicine
  • Molecular Biology

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