Catalytic antibody components, methods for producing catalytic antibody components, methods for using catalytic antibody components, in particular, single chain and smaller components are disclosed. Catalytic antibody components able to promote the cleavage or formation of an amide, peptide, ester or glycosidic bond, and which are prepared from monoclonal catalytic antibodies, catalytic autoantibodies or by site-directed mutagenesis are disclosed. Methods of using catalytic antibody components alone or in combination with other antibody components or other biological moieties are disclosed.