Protein molecules are very large and, in the case of the so-called "conjugated proteins" in particular, their structure is very complex.
"The Chemistry of Plant Life" by Roscoe Wilfred Thatcher
Therapeutic monoclonal antibodies can be conjugated with a variety of molecules including small-molecule drugs, radionuclides, peptides, other proteins (protein toxins, enzymes, cytokines), and polyethylene glycol.
The vaccine is composed of a chemical conjugate of EGF and a carrier protein (rP64k), designed to trigger an anti-EGF antibody response.
Nanotube molecular transporters: Internalization of carbon nanotube-protein conjugates into mammalian cells. J.
Carbon Nanotubes in Biology and Medicine: in vitro and in vivo Detection, Imaging and Drug Delivery