Enzyme studies with antibody

In this section is an overview of some historical aspects of enzyme studies with special emphasis on new methods of purification, structure determination, and research on the reaction mechanism of an enzyme. Enzyme application for medical and industrial use and development of novel enzymes such as catalytic RNA (ribozyme) and catalytic antibody (abzymes) are also briefly described. 

Using irreversible inhibitors to map the active site (p. 228) Enzyme studies with catalytic antibodies (p. 232)... 

Biological interactions between molecules are stereo-specific the fit in such interactions must be stereo-chemically correct. The three-dimensional structure of biomolecules large and small—the combination of configuration and conformation—is of the utmost importance in their biological interactions reactant with enzyme, hormone with its receptor on a cell surface, antigen with its specific antibody, for example (Fig. 1-22). The study of biomolecular stereochemistry with precise physical methods is an important part of modem research on cell structure and biochemical function. 

All plants contain a PEPCase enzyme which, among other likely roles (Vidal et al., 1986), serves to replenish tricarboxylic acid cycle intermediates that are consumed during ammonium assimilation (Latzko Kelly, 1983). The role of this enzyme, other than its presumed housekeeping function, has not been studied in any detail and its activity is probably not controlled by environmental factors. Isoforms of PEPCase have been observed in many plants (C3, C4 and CAM) for example, in rice five isoforms have been detected immunologically and in most plants two to four bands that react with anti-PEPCase antibodies are found (Matsuoka Hata, 1987). It is not clear how these isoforms arise, e.g. by post-translational modification of one form, or whether all of these forms are products of different genes. The housekeeping-type PEPCase enzyme, concerned with anaplerotic functions, is distinct from other PEPCase enzymes that function in plants with C4 and CAM metabolism (see below). 

The binding constant between FITC-labeled bovine serum albumin and its monoclonal antibody was determined using ACE with LIF [14], Interaction of the enzyme cyclophilin with the immunosuppressive drug cyclosporine A was quantitatively assessed by CE with UV detection [15]. In the latter case the authors showed in particular how the difference between the sensitivity of the detector and KD of the studied system can severely hamper the correct determination of binding constants. 

Individual animals immunized with the same substance can produce antibodies that may differ in affinities, titer, and specificities. " Such differences are appeu-ent with antibodies studied by the more classical physical chemical procedures. However, even among anti-enzyme sera harvested from individual rabbits that had been immunized with -lactamase, some were found to neutralize the activity of the enzyme, others to stimulate its activity, and still others were stimulatory and then inhibitory at higher concentrations." In radioimmunoassay, each antiserum from an individual animal must be characterized separately to select those that have the proper affinities and specificities. The production of monoclonal antibodies by hybridoma technology can yield molecules with defined specificities and affinities. As this technology becomes affordable for the average research laboratory, problems associated with antibody heterogeneity are due to diminish. 

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