Abzymes Research is a New Field of Enzyme Engineering
Posted by kiko on November 26th, 2021
Abzyme, also known as catalytic antibody, is a type of immunoglobulin with catalytic ability, that is, an antibody with catalytic activity prepared through a series of chemical and biotechnological methods. It not only has the corresponding immune activity, but also can catalyze a certain chemical reaction like an enzyme.
In 1946, Pauling used the transition state theory to clarify the essence of enzyme catalysis. That is to say, the enzyme has catalytic activity because it can specifically bind and stabilize the transition state of a chemical reaction, thereby reducing the reaction energy level.
In 1969, Jencks conjectured on the basis of the transition state theory that if an antibody can bind to the transition state of the reaction, it can theoretically acquire catalytic properties. Abzymes have typical enzyme reaction characteristics, specificity of binding to ligands, including stereo specificity, specificity of antibody enzyme catalytic reactions, which can reach or exceed the specificity of natural enzymes, and also have high-efficiency catalysis.
Enzymes for antibody research have typical enzymatic reaction characteristics:
1. The specificity of binding to the substrate. Including the stereo specificity, the specificity of the abzymes catalyzed reaction can reach or exceed the specificity of the natural enzyme.
2. Efficient catalytic performance. Generally, the reaction speed of antibody-catalyzed reaction is 104-108 times faster than that of non-catalytic reaction, and some reaction speed is close to the speed of natural enzymatic reaction.
3. Abzymes also have Michaelis equation kinetics and pH dependence similar to those of natural enzymes.
There are three main methods for converting antibodies into enzymes: induction, introduction, and copy. The induction method is to use reaction transition state analogues as haptens to make monoclonal antibodies, and to screen out monoclonal antibodies with high catalytic activity. The introduction rule uses genetic engineering and protein engineering to introduce a catalytic gene into the antigen binding site of a specific antibody to obtain a catalytic function. The copy method is mainly designed according to the antigen-antibody complementarity during the antibody production process. Pollack et al. used nitrophenol phosphocholine ester as a hapten to induce the production of monoclonal antibodies. After screening, they found an abzyme that speeds up the hydrolysis reaction by 12,000 times.
Abzymes can catalyze a variety of chemical reactions, including ester hydrolysis, amide hydrolysis, acyl transfer, light-induced reactions, redox reactions, metal chelation reactions, and so on. Among them, some reactions could not proceed at all in the past because there was no biocatalyst.
The research of abzymes is a brand-new field of enzyme engineering, which provides people with a reasonable way to design proteins suitable for market needs, that is, artificially design and produce enzymes. Utilizing the high specificity of the antibody produced by the animal immune system, a series of highly specific abzymes can be obtained, so that abzymes are continuously enriched. Abzymes can selectively cleave the peptide bonds of the virus coat protein, thereby preventing the virus from binding to target cells. The immobilization of abzyme has been successful and will greatly promote the process of industrialization.
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About the Authorkiko
Joined: November 27th, 2018
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