A method for increasing the rate of chemical reactions involving the conversion of at least one reactant to at least one product involves contacting the reactant with an appropriate monoclonal antibody under conditions permitting the formation of a complex between the antibody and the reactant. The complexed reactant is converted to the product which is then released from the complex. The monoclonal antibody may employ a cofactor and may be directed to a known substrate of an enzyme. Methods for preparing such monoclonal antibodies are also disclosed.