a chemical conjugate of avidin and the ribosome-inactivating protein, saporin
Avidin is a glycoprotein found in egg white and in tissues of birds, reptiles, and amphibians. This protein is composed of four subunits, each of which can bind one molecule of biotin. Biotin, a 244-dalton vitamin found in tissue and blood, binds with high affinity to avidin. In fact, the avidin-biotin interaction is the strongest known noncovalent biological interaction (Ka = 1015 M-1) between protein and ligand. The bond formation between avidin and biotin is rapid and essentially non-reversible, unaffected by most extremes of pH, organic solvents, and denaturing reagents. Extensive chemical modification has little effect on the activity of avidin, and biotin’s small size allows it to be conjugated to many proteins without significantly altering the biological activity of the protein. The avidin-biotin interaction has found extensive use as a research tool. A variety of molecules, including lectins, proteins, and antibodies, can be biotinylated and reacted with avidin-labeled probes or other detection reagents for use in biological assays.
Effective Tool: Using avidinylated SAP and specific targeting agents that have been biotinylated, specific cytotoxins can be created JUST BY MIXING!