Abzymes

Antibodies are proteins and, like enzyme and receptor proteins, they have binding domains (regions) where they bind other molecules.
Antibodies bind molecules called antigens and can bind small molecules (haptens) or small parts (determinants) of high molecular weight antigens, which may be attached to cells. Catalytic antibodies or abzymes are an additional class of biocatalyst because they have distinct catalytic properties.They catalyse several reactions, including hydrolysis, cyclisation reactions, elimination reactions and synthesis.
Comparative studies between enzymes and abzymes indicate that enzymes have varying levels of specificity built into their structure, whereas antibodies have much greater recognition qualities. It seems likely that enzymes and antibodies are ‘molecular cousins’ that evolved from a common ancestor with catalytic and recognition properties. Enzymes probably evolved to concentrate on catalysis and their recognition property adapted to provide specificity. Antibodies evolved the recognition property to a very high degree and retained useful elements of catalysis.
Comparison of the properties of enzymes and abzymes will provide new understanding of the selectivity process inherent in enzyme specificity,Abzymes could have exciting applications in many areas of biotechnology, medicine, analytical biochemistry and molecular biology.
In particular, enzyme specificity is limited to that already provided by Nature and often such limitation restricts the range of possible catalysis. With protein engineering, it will be possible to alter and improve the specificity of key enzymes and improve the catalytic power of useful
abzymes. Antibodies have a vast repertoire of highly specific binding functions, which can be used to increase further the portfolio of biocatalysts for the biotechnologist’s toolkit.
Biosensors are an obvious example where abzymes could provide new improvement in recognition of analyte (molecule to be measured) and thereby increase the range of analytes that can be detected and measured.
Enzyme-based biosensors are limited in scope and tend to discriminate between low molecular weight molecules. Abzyme-based biosensors, on the other hand, have considerable scope and will be able to discriminate between toxins, viruses, microbial cells, native and foreign proteins, nucleic acids, human cells, cancer cells, etc. Evolution has shaped antibodies for a particular role in Nature so it is not surprising that abzymes have less catalytic power than enzymes and have a tendency not to release product quickly after catalysis. However, unlike enzymes, antibodies have common gross protein structural features so a single immobilisation
method may be more readily applied to different abzymes.