Inspired by camel blood
Targeted medical diagnostics and treatments using antibodies are an established alternative to conventional drugs.
Researchers from the Institute for Chemistry and Bioanalytics have tested a new class of ‘Sybody’ antibodies which were developed in Markus Seeger's research laboratory at the University of Zurich and which are derived from camels. These fragments are one-tenth the size of conventional antibodies and have several advantages that make them good candidates for immunological diagnostics or disease treatment.
Antibodies are proteins which an organism uses to defend itself against foreign agents such as bacteria. The function principle is simple: bacteria and other extraneous entities have molecules on their surface called anti- gens, which have a characteristic shape. The immune system forms specific antibodies against these structures that fit their form exactly and dock to them. This selectivity, as well as the fact that they cause few side effects, is what makes antibodies so interesting for medicine. They are already used in the treatment of rheumatism, cancer and multiple sclerosis for example and as a vaccine against infectious diseases. Coupled with a radionuclide, they make tumour cells or inflammation visible.
Antibodies have a characteristic Y-shape consisting of several small fragments called domains. The outermost part of the two short arms of the Y is critical for the high degree of selectivity of the antibodies, which means they only dock to certain antigens. “This protein – the small, exactly fitting part of the antibodies – is sufficient by itself for binding to the corresponding surface structures,” explains Daniel Gygax, biochemist at the HLS. Gygax and his team used biophysical methods to characterise the camel antibody fragments modified by Seeger's research group. In particular, the researchers investigated how quickly these Sybodies bind anti- gens and when the binding releases. They chose Sybodies because their selective fragment consists only of a polypeptide chain and can thus be produced in bacteria easily and quickly. Due to their size, the small Sybodies have other advantages: they enter tissues faster, and are metabolised faster.