Monoclonal catalytic antibodies,

The safety of the cocaine vaccine TC-CD in former cocaine abusers has been evaluated in a Phase I clinical trial, and it was determined that the vaccine was well tolerated with dose-related increases in antibody levels.65 Two Phase II clinical trials have now been conducted.66,67 The vaccine was again well tolerated and subjects reported a reduction in cocaine s reinforcing effects. The antibody levels were detectable after the second dose, peaked at 8 to 12 weeks, and remained elevated for up to 6 months preliminary findings indicated a negative association between antibody level and cocaine use. Other anti-cocaine vaccines in development include a blocking antibody (ITAC-cocaine) and a monoclonal catalytic antibody (15A10). 

Sastry, L., Alting-Mees, M., Huse, W.D., Short, J.M., Sorge, J.A., Hay, B.N., Janda, K.D., Benkovic, S.J., and Lerner, R.A. (1989) Cloning of the immunological repertoire in Escherichia coli for generation of monoclonal catalytic antibodies Construction of a heavy chain variable region-specific cDNA library. Proc. Natl. Acad. Sci. USA 86, 5728-5732. 

Several homogeneous synthetic artificial enzymes " and catalytic antibod-igsi05,i06 proteinase activity have been reported. The monoclonal catalytic antibody prepared with a phosphinate hapten exhibited optimum activity at pH 9.5. The measured with an amide substrate at pH 9 and 37 °C was 1.65 x 10" s" Thus, the half-life is 49 days when the substrate is fully complexed to the active site of the catalytic antibody. 

Another approach was to develop catalytic monoclonal antibodies, using organophosphorus transition-state analogs to elicit the specificity needed. This work produced one clone that apparently displayed the desired specificity, but it was subsequently lost and could not be reproduced eventually the effort was abandoned [9], More recently another monoclonal catalytic antibody with similar characteristics was reported [16],... 

Structure correlation to map reaction pathways might become important in the field of the monoclonal catalytic antibodies [145, 146]. These proteins are produced by the immune system to bind molecules which resemble the transition state of a chemical reaction. They show catalytic properties with high substrate specificity. Reactions can be imagined for which a biochemical catalyst is not yet known (e.g. the Diels-Alder reaction). The rational design of catalysts for these reactions requires detailed information about possible transition-state structures, geometrical and energetic aspects of the ligand/receptor interface and results from structure/reactivity relationships which are available from structure correlation. 

In a study designed to produce monoclonal antibodies which would catalyse the hydrolysis of phosphorus nerve agents, Moriarty et al. used a synthetic strategy involving a monocyclic phosphorane as hapten for the production of a monoclonal catalytic antibody based on the T.S. for phosphonate hydrolysis. These haptens (18 and 19), which are effective catalysts for the hydrolysis of Soman [Bu MeCHOPMe(0)F], were generated from the reaction of (15) with the protected 3(S) aminoalcohols (16 and 17). ... 

Amino-l-cyclohexylmethylphosphonic acid diethyl ester was utilized for the preparation of hapten 1, recently employed to induce the first monoclonal catalytic antibodies capable of catalyzing peptide bond formation[97]. The key steps of the synthesis of 1 include (a) preparation of scalemic a-aminophosphonate, (b) generation of the p-nitrobenzyl ester, (c) installation of a suitable second phosphonate ester linkage, (d) M-acylation with glutaric anhydride. 

Many of the 60 known reactions catalyzed by monoclonal antibodies involve kinetically favored reactions e.g., ester hydrolysis), but abzymes can also speed up kinetically disfavored reactions. Stewart and Benkovic apphed transition-state theory to analyze the scope and limitations of antibody catalysis quantitatively. They found the observed rate accelerations can be predicted from the ratio of equilibrium binding constants of the reaction substrate and the transition-state analogue used to raise the antibody. This approach permitted them to rationalize product selectivity displayed in antibody catalysis of disfavored reactions, to predict the degree of rate acceleration that catalytic antibodies may ultimately afford, and to highlight some differences between the way that they and enzymes catalyze reactions. 

Catalytic antibodies, like enzymes, must be isolated and purified to homogeneity before they can be studied. Initially this was done by using the hybridoma technique for isolation of monoclonal antibodies (Box 31-A). After induction of antibody formation by injecting a selected hapten into a mouse, large numbers of monoclonal antibodies had to be tested for catalytic activity. Even if several thousand different monoclonal antibodies were tested, only a few with catalytic properties could be found.1 Newer methods have incorporated recombinant DNA techniques (Box 31-A) and use of combinatorial libraries and phage display.) Incorporation of acidic or basic groups into the haptens used to induce antibody formation may yield antibodies capable of mimicking the acid-base catalysis employed by natural enzymes. 0... 

The idea that antibodies also can stabilize the transition state of a reaction, that they feature a sterically or electronically complementary active center to the ratedetermining transition state just like enzymes, has existed since 1969. This concept of catalytic antibodies could be investigated only after the advent of monoclonal antibodies. The capability to raise molecularly uniform antibodies instead of polyclonal sera... 

Many examples of the use of catalytic monoclonal antibodies for a variety of organic transformations and especially for Diels-Alder reactions have been described in the last years since its discovery by Lerner and Schultz [563], Recently, a hetero Diels-Alder reaction of an arylnitroso dienophile 9-4 and ( )-piperylene 9-3 to give the two regioisomeric cycloadducts 9-5 and 9-6 in the presence of a catalytic antibody has been published by Pandit and his group [564]. The most successful hapten used was the bridged compound 9-7 (Fig. 9-2). 

Scheme 3. The highly-ordered transition state associated with the Diels-Alder reaction has made it a natural target for work in the field of catalytic antibodies [15]. Indeed, Hilvert [15a] has reported recently the first successfully antibody-catalyzed Diels-Alder reaction. Monoclonal antibodies elicited to the boxed hapten 14 provided both acceleration of and multiple turnover of the cycloaddition between tetrachlorothiopene dioxide and IV-ethyl maleimide. The initial adduct decomposes by the chelotropic-extrusion of sulfur dioxide affording the dihydrophthalimide derivative 13...

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