Antibody-mediated activation of genetically defective Escherichia coli beta-galactosidases by monoclonal antibodies produced by somatic cell hybrids.

AUTOR(ES)

Accolla, R S

RESUMO

Six hybridomas producing monoclonal antibodies against Escherichia coli beta-galactosidase (beta-D-galactoside galoctohydrolase, EC 3.2.1.23) have been derived from two separate somatic cell fusions. Three of these antibodies can activate defective enzymes produced by strains of E. coli carrying Z-gene point mutations. In antigen excess, one monoclonal antibody shows similar enzyme binding and mutant-activating capacity. Characteristically, the former reaction has a 200-fold higher equilibrium constant. These data provide direct evidence that the enzyme-activation reaction is a single-hit event in which one antibody site favors the correct conformation of one active center of the enzyme. Because each "activating" hybridoma is able to activate several but not all point mutant enzymes tested, it appears that the correction of the genetic defect is produced by binding key sites of the protein three-dimensional structure rather than the sites affected by the mutation.

Documentos Relacionados

• Antibody-mediated activation of a defective beta-D-galactosidase extracted from an Escherichia coli mutant.
• Study of antibodies against human melanoma produced by somatic cell hybrids.
• Antibody-mediated activation of a defective beta-D-galactosidase: dimeric form of the activatable mutant enzyme.
• Antibody-mediated immobilization of Campylobacter fetus: inhibition by a somatic antigen.
• Effect of imipenem on monoclonal antibody-mediated protection against Escherichia coli O18K5.